Umm I don't know for sure. I just went with the "Latest stable release" date on ...

jonknee · on July 7, 2010

http://android-developers.blogspot.com/2010/06/froyo-code-dr...

"Today is one of those days that has my heart racing; we’ve just released the source code for Android 2.2."

...

"Posted by Tim Bray on 23 June 2010"

alunny · on July 7, 2010

releasing the source != pushing out over the air OS updates

commandar · on July 7, 2010

Wiki is wrong, then. The official 2.2 update for the Nexus One only went out about a week ago, and Froyo code was added to AOSP about a week before that.

http://www.pcworld.com/article/200041/google_android_22_froy...