Neowin has released a report that claims Microsoft is working on two new applications for the AppStore, one being a Bing application and the other for Windows Live Messenger on the iPhone. Unfortunately the applications won't be released until March, which should time nicely with their release of Windows Live Wave 4 updates.
"Everyone understands the popularity and the pervasiveness of the platform," said Microsoft principal group program manager David Raissipour, following a Bing event Wednesday. "We are actively working on it."
There should be more news and screenshots even over the next week, so I'll try to keep this post updated as I receive more news. Stay tuned!