MarkSpace has been making PDA-to-Mac syncing software for some years. First the Sony Clie version, then the Windows Mobile version and now they're working on a solution to sync the BlackBerry to the Mac. When it's released, it will sell for $39.95, but in the meanwhile you can try out the public preview (pre-release version) for free here. The download instructions and URL are in the top post in the Mark/Space forum at that link.

Here's their press release:

PREVIEW: THE MISSING SYNC FOR BLACKBERRY PUBLIC PREVIEW
Our fans have been asking for a BlackBerry edition of The Missing Sync for
years, and the development of that very product is finally in the home
stretch! A public preview of The Missing Sync for BlackBerry is now
available for download and testing from the Mark/Space website.

Like other members of The Missing Sync product family, The Missing Sync for
BlackBerry synchronizes contacts, calendar events, tasks and notes with
BlackBerry devices that have USB ports.

Owners of multimedia-capable BlackBerry handsets, such as the BlackBerry
Pearl (8100) and the new 8800 series, can also use The Missing Sync for
BlackBerry to synchronize iPhoto albums and iTunes playlists containing
unprotected music and podcasts to the BlackBerry?s microSD card.
Additionally, photos taken with the cameras in these devices can be
imported by The Missing Sync directly into iPhoto or a folder in the Mac?s
Finder.

The Missing Sync for BlackBerry will sell for $39.95 when it?s released
later this quarter, and we?ll be providing discounted ?crossgrades? for
owners of The Missing Sync for Palm OS and The Missing Sync for Windows
Mobile.

In the meantime, individuals who are interested can download and try the
public preview release from the Mark/Space website. If you do try out the
preview release, we?d appreciate receiving your feedback in our forums
<http://announce.markspace.com/lists/lt.php?id=N08DXFYGBQpUHwZaTgBVC1dR>,
so we can make this our best release yet.

To learn more, read about known issues and download the preview release,
please visit:
<http://announce.markspace.com/lists/lt.php?id=N08DXFYGBQpSHwZaTgBVC1dR>.

Note: The download is pre-release software and may contain unknown bugs.
Mark/Space strongly recommends that users back up their data before testing
the preview release.