Agree with ragingray. I have always used backup assistant, so here's how I did it, which is probably a little more of a hassle:
Signed on to backupassistant and dowloaded .CSV file of all my contacts.
Imported CSV file into gmail, and then synced.
[Make sure you go into People, Menu, view, and check Google]
Now I had 2 of every contact showing. You have 2 options at this point, as I see it:
(1) People; Menu; View; Check Google; Uncheck Phone, or
(2) Delete all of your contacts on Backup Assistant (leaving only your Google contacts and no duplicates -- just remember to save that csv file just in case).