Web-based photo editing suite Picnik announced today that it has been acquired by Google for an unspecified amount that Picnik CEO Jonathan Sposato called a “very, very happy number.”

The startup opened in 2005 and was chosen to be Flickr’s default photo editor in 2007 when Yahoo was introducing a host of new features to the popular photo sharing site. Long before Adobe released its Web-based version of Photoshop, Picnik was already going strong.

Google will reportedly leave Picnik as its own brand for now, and allow it to be integrated into third party sites, including Flickr. Brian Axe, Product Management Director for Picasa, today said there will be no announcements about any significant changes to Picnik today, but Google will be “collaborating closely with them to improve the online photo editing experience on the Web.”

It’s the second piece of news today that has involved Google and Yahoo in a strange symbiosis.

The first bit came in a rather unlikely place: a Motorola Backflip unboxing. Adding to the Backflip’s reputation as the strangest Android device to date, the default search engine is Yahoo and not Google.

Naturally, Motorola’s MotoBLUR interface is built on the open source Android framework so a “Google Experience” should not necessarily be expected, but it is nonetheless interesting to see a Yahoo home screen widget on Android instead of a Google one.

For now, it appears that Google’s Picasa and Yahoo’s Flickr will share a photo editing suite as well.