"The following works for 10.6.8 (successfully tested by several users):
Open Keychain Access (you can search for it using Spotlight).
Under Category, select Passwords
In the Applications listed, double-click Google Drive: this will open a smaller settings window
Click the Access Control tab
Select "Allow all applications to access this item" and click Save Changes (you may need to enter your password to confirm)."
"Scheduled Release track features update 12/14/12
Released on 12/14/2012
Gmail: Users using the new compose experience in Gmail now have the ability to insert files up to 10GB from Drive directly into an email . Gmail will automatically check that recipients have access to any files being sent.
The following features are intended for release to these domains on December 18th:
No new features to announce"