Amazon predicts Staff of Kings in June 04 Feb, 2009 / Comments: 2
In conjunction with LucasArts' announcement of the game, Amazon.com has put up new product listings for Indiana Jones and the Staff of Kings, complete with placeholder box art. The Wii version is listed as costing $49.99, and all other versions as $29.99, with a suggested simultaneous street date of June 2nd.
This being the product listings of an online retailer it should by no means be taken as gospel, but nothing about Amazon's info seems particularly fishy so that date is probably a decent estimate (even with the "Spring 2009" claim appended to the end of the new trailer).
I don't know, seems a bit late to me.