I use OS X (10.4.11) and I've always used PocketMac to sync between my BB Pearl 8100 and my computer. I just got a G1 and I wanted to import my contacts. The easiest way I could find was to export the contacts from Address Book (select the records you want, choose File -> Export), then convert the resulting VCF file to a CSV file (
Online vCard Converter) to a CSV. I could then log into Gmail, go to Contacts, choose Import, and select the CSV file. The contacts showed up on the phone automatically.
Not a syncing method as such, but it should help migrate your BB stuff to the G1, which is the big thing.
cheers!