Ask TUAW: how to sync between Address Book and Gmail

Hawk Wings has an interesting roundup post covering a number of individuals who are dumping Apple's Mail in the name of Gmail for various reasons. While I've been experimenting with the same thing over the last couple of weeks, I've run into a hangup that I felt worthy of an Ask TUAW post. Since more and more of us are adopting web services for daily operations, I thought y'all might have some thoughts on my situation: I love web services, especially ones like Gmail, but now that I own a Motorola RAZR that can sync contacts and events with OS X, I'm on the hunt for an easy way to keep my contacts synchronized between Address Book and Gmail. I know there are basic export apps that are handy for that initial dump from Address Book to Gmail, but I don't know if using that same method a second time will simply double-up all my Gmail contacts. A two-way solution would be ideal, allowing Address Book, Gmail and my RAZR to dance in perfect geeky harmony.

So what say you, TUAW readers? Have any of you found a way to keep all this software in sync?