According to Japanese blogs Cave is working on a 360 port of two legendary shooting games: DoDonPachi DaiOuJou and Ketsui. It's still just a rumor (these ports don't have show up at the recent Cave Festival held last december in Akihabara) but it's pretty credible since Ketsui is being ported to Nintendo DS and the Microsoft console is considered by many Japanese producer a good (and reasonable) chance to get into the western market without spending huge money to pay Sony license. What is still not clear is if these titles will get the Live Arcade path like Trigger Heart Exelica or will be released on disc (maybe in a multi game format).
Brandon from Insert Credit states that: This is now confirmed Famitsu, and they're coming this year. Huzzah! The ports are being done by 5pb and the producer is Masaki Sakari. The Famitsu article says they've been 'hard at work' on arcade properties as well, so we shouldn't be worried.