It's probably Star Wars 1313
, the game Lucasfilm trademarked earlier this month.
It's rumored to be a game based on Boba Fett (due to him using the alias CT-1313 in a Star Wars novel).
I'm just hoping that whatever is revealed at E3 was developed by LucasArts in-house. It's their 30th anniversary this year, and it would be a shame to celebrate it with only a licensed title from an outside developer.