Microsoft CEO Steve Ballmer made an unexpected appearance at Research In Motion’s BlackBerry World this morning to tout a new deal to integrate Bing with RIM’s OS and make it the default engine for maps and search. It certainly seems like a good deal for both players: Microsoft gets a big new distribution channel for Bing, while RIM can offer a more comprehensive mobile experience without having to use Google, which is gaining tremendous momentum. Expect to see more of these kinds of deals as the smaller platform operators try to build more comprehensive mobile offerings to compete with Apple and Google — the two most powerful players on the field.