It seems the April issue of Official Xbox Magazine has some information about the highly anticipated XBLA release Ikaruga. Specifically, it sounds like the game will be coming out very soon, as the magazine notes the game is already available with a graphic that reads "Out Now." It doesn't get much clearer than that. Unfortunately, given the nature of magazine lead times (people get April issues in March, etc.) it's hard to say exactly when Ikaruga will show up, but it's probably safe to say it should be out before the end of April. Oh, and for what it's worth, OXM gave Ikaruga a 9 out of 10, so things are looking up.
Update: Upon closer inspection, the review appears to be in the UK Official Xbox Magazine.