Google released Picasa for Mac. Google previously offered both a standalone Picasa Web Albums uploader and an iPhoto plugin for Mac users, Picasa for Mac finally brings all of the sharing and sync features of Picasa to the millions of Mac OS X users who use Picasa Web Albums.
Picasa for Mac looks and works much like Picasa on other platforms, and offers trademark Picasa features — such as non-destructive editing, and the ability to keep track of photos anywhere on your hard drive, then automatically account for new images as you add them.
Picasa for Mac is still in Google Labs, but Google wanted to get an early version out to folks attending Macworld 2009. More details on Google Photos blog. More Macworld 2009 announcements.