What is the best way to integrate your MacBook your Palm database and your Blackberry?

MarkSpace has a "MissingSync" line of products for integrating Macs and various PDA products. Your first problem, however, is that you're trying to use your Mac as a conduit between two products that weren't designed to talk to each other - Palm software and a Blackberry PDA.

Your best bet is to use your Mac to its fullest advantage. Make your OSX address book be your "source of truth", and sync your Palm devices and software to it (using the MissingSync for Palm OS product) and sync your Blackberry device to it (using the MissingSync for Blackberry product).

I've never actually tried to do what you're doing but it seems like it should work.