In the Wikipedia article history, I can find the edit you mention at 21:12 and the edit freeze at 21:45, but not the edit you mention at 21:48...
This page should show the relevant part of the history: http://en.wikipedia.org/w/index.php?title=Michael_Jackson...
I would say Wikipedia confirmed the death at 22:27, just after MSNBC and CNN, which is consistent with Wikipedia policy of relying on mainstream sources.