signal in your hands

The first order of business is to go to to the Apple menu in the upper left corner of your screen, then select System Preferences. From there, select the Bluetooth pane under Hardware and make sure that Bluetooth is both On and Discoverable.

On your BlackBerry, find and open the Set Up Bluetooth application. If you don't see it, your phone might not support Bluetooth or it might be hidden; open the menu on your home screen and select Show All Icons to make sure. If you find the Set Up Bluetooth application, select it and open the menu, then click on Hide Icon to unhide it. You can then select Show All Icons again to rehide them.
When you first open the application, it will ask you to ensure that the Bluetooth device is in pairing mode, which is what we did when we set the Mac to be On and Discoverable. Hit OK, and it will search for available devices. Bluetooth is a short range technology, so make sure you're standing close to your Mac. Once it finishes searching, it will display a list of all the devices it found. Likely your computer will be the only one on the list. If you've named your computer it will show up as whatever you named it (for instance, I named mine Empyrean), otherwise it will be something like Devin Kent's Computer except, of course, with your name instead of mine.
Once you've selected your computer, it will ask you to enter a numeric passkey. The passkey can be whatever you want -- I normally use 1234 -- and it doesn't have to be secure because it's only ever used once. Put in a number, and you'll immediately see this dialog screen on your Mac:
Enter the same passkey that you entered on your BlackBerry and hit the Pair button. Congratulations, you've paired your phone and your Mac! To double check, head over to the Bluetooth preferences on your Mac and you should see your phone in the list on the left.
And the same on your BlackBerry.
If you don't see anything in the list, or if you get an error saying that pairing failed, just go the process one more time. The connection between the two only lasts for a very short while, so if you take too long to enter the passkey on your phone or on the Mac it will give up and disconnect.
 
From BlackBerry to Mac
Once you've successfully paired the two, it's time to start transferring files. Transferring from the BlackBerry to the Mac is very simple. Open the Media manager on your BlackBerry and find a picture or song or other file you want to transfer, then open the menu and select Send Using Bluetooth.
It will pop up a list of devices that you've paired with, so select your computer and wait. After thinking for a moment, it will tell you it's waiting for your computer, at which point you'll see something like this show up on your Mac:
Hit Accept and then, if you're anything at all like me, you can try to watch the phone and computer screen at the same time to see if the progress bars match up (I think that they do). When everything's done, the file will be in the Documents folder in your Home folder and both phone and Mac will say the transfer was successful.
 
From Mac to BlackBerry
Sending files from your Mac onto the BlackBerry is slightly trickier, but still a relatively simple process. On the BlackBerry, open your Media manager and select either Music, Ringtones, Video, or Pictures -- it does matter which, because the system will either put the file in the right place itself or ask you where to store it. Once you've selected one, open the menu and select Receive Using Bluetooth -- it's way down near the bottom of the list.
It will tell you it's waiting for a connection, so pop over to your Mac and find the file you want to send. Right-click or control-click on the file to open a contextual menu, then navigate down to the sub-menu called More. In that menu, there will either be a selection called Send "filename" to Bluetooth Device... or there will be another sub-menu called Send "filename" to... which will have your phone in the list.
Your BlackBerry will ask if you want to recieve the file and will prompt you for a location to save it. Pick a spot and your transfer will immediately start.
Unfortunately, this is the place where you're most likely to run into bugs. I almost never have a problem transferring files to the Mac, but transfers to the BlackBerry tend to stall about half the time, never to resume. Usually you can abort the transfer and just try again to fix it up. (Be sure to check that it didn't leave half a picture lying around somewhere.) Also, files will occasionally fail instantly with no error message. This usually means that your Berry doesn't have enough space remaining to store the file, so keep that in mind.
 
Troubleshooting
In addition to the above, you might run into a couple other problems. Occasionally after a transfer had stalled, you'll no longer be able to transfer files at all. The simplest solution is to turn Bluetooth off and then back on, on both the Mac and the BlackBerry; on the Mac, it's in the Bluetooth preference pane and on the BlackBerry there's an application on the home screen called Turn Bluetooth Off (or On if it's already off). If that doesn't fix it, delete the phone from the Mac and vice versa. On the Mac, simply click the little minus sign in the Bluetooth preferences while the BlackBerry is selected.
On the BlackBerry, open the Options application, select Bluetooth from the list, then open the menu while your computer is selected and select Delete Device.
Then re-pair the devices and try again.
Finally, if you have troubles during the pairing process, you can try to pair them from the Mac rather than the BlackBerry. It's a very similar process. First turn Bluetooth on for both the Mac and BlackBerry, then open the Options application on your BlackBerry and select Bluetooth. Open the menu and select Options from there, then make sure your phone is set to Discoverable.
Back on the Mac, open the Bluetooth preferences and click Set Up New Device or, if you've already got a device paired, the little plus sign on the bottom left. The Bluetooth Setup Assistant will open and walk you through the process. Hit Continue on the first screen, the make sure Mobile phone is selected on the second screen and hit Continue again.
The next screen will show a list of available devices, and hopefully your phone is one of them. Select it and press Continue again, then check your phone again: it should be asking you for a passkey. Once again, enter anything you can remember for the next 10 seconds, then enter the same thing on the Mac. Et voila, you should now be paired up and ready to transfer files.
If none of the above works, trying moving any cordless phones and any other mobile phones away from your computer, or bringing your BlackBerry closer. Bluetooth is based on radio waves and it might simply be a case of interference. Other than that, your best bet is to get one or both looked at by a service technician, because their antennae might be busted.
That's all, folks! You're not able to do much else with Bluetooth and the Mac. Neither PocketMac or The Missing Sync -- the Mac replacements for the BlackBerry Desktop Manager on PCs -- supports syncing over Bluetooth yet, so you're stuck with a USB cable for transferring your address book or calendar. Still, it's pretty useful for quickly transferring over all your pictures, or for uploading a new ringtone to spice up your BlackBerry.