RIM seemed less likely but given their need for a new phone OS, it seemed like a pretty easy fit. Corporate culture might have been a factor against them doing this deal, hard to say.
HP's not the sort of company that can enter a new market like this and turn it on its ear, but maybe I'm wrong. They did have the foresight to buy DEC Alpha, which seemed like a great fit, but then they did nothing with it.
Here's hoping for the best.