Update 2: Sometimes you can be right for the wrong reasons. Apple has now for-real announced Steve for the keynote at WWDC 2011.
Update: GigaOm has retracted the story; their post was indeed based on the 2010 WWDC press release. Oops.
It's always a treat when Jobs can participate in Apple events. His ongoing health issues and medical leave from Apple make him less of a guaranteed speaker and more of a delightful surprise when he feels well enough to appear.
Unfortunately, GigaOM jumped the gun on this one. There is no official announcement from Apple and the only press release showing a SteveNote at WWDC is from last year (thanks to Ars Technica's Jacqui Cheng for pointing that out).
We've reached out to Apple for comment and will update if we hear anything. Not to say for sure that Steve wouldn't appear at WWDC, but as far as we know right now, he's not. [And now he is.]