I can't be sure what the announcement is. The buzz I started hearing originated from the Spike announcement I believe, which mentioned new Star Wars "franchise". That leads me to believe this announcement has to do with a new game not a sequel... and it may have something to do with Bounty Hunters with Lucas Arts trademarking "Star Wars 1313" not too long ago. The fett reference screams from that. Boba used the alias CT-1313 (http://starwars.wikia.com/wiki/CT-1313
). There was also a bunch of domains registered "StarWars1313.com"... "1313StarWars.com"... etc.
The announcement for this game will be tomorrow on Spike with a full reveal at E3. With that said, I'm still hearing rumors that there will be an announcement for a game from Lucas Arts at E3 separate from the full reveal of the announced game tomorrow May 31st.
That's how rumors go once the rumor mill starts turning. No proof.. only speculation... and wait.
If you're correct, I'm hoping it's Star Wars Bounty Hunter 2 (1 was incredibly good), playing as Boba. And as they've started the Boba Fett is Dead comic storyline, more Boba could well make sense.