From February 27th 2011 - March 7th 2011, Celebi will be downloadable at GameStop across America. This download will be available on Diamond, Pearl, Platinum, HeartGold, and SoulSilver.
This Celebi can activate two events:
* The Giovanni event in HG/SS at Ilex Forest, where the player learns of the backstory of Team Rocket
* Pokemon Black and White's (English Version) Zorua event in Castelia City when it comes out.
Celebi will be at Level 50, OT GAMESTP, Trainer ID 22710, holding a Jaboca Berry. It will know Leaf Storm, Recover, Nasty Plot and Healing Wish.
Source:
http://www.serebii.net