Apple are not the competition.
The iPhone is a walled garden with its own hardware, apps and such. It's a niche product. A bloody big niche I'll grant, but a niche all the same. There's only so much market share it can pick up as the OEMs can't use the O/S on their products and they all want to stay in business. Also, being controlled in toto by Apple it's utterly damned useless to anyone who isn't interested in being locked in tighter than a gnat's chuff.
RIM are not the competition. They're a big fish in a small pond of their own devising, i.e. business types who want a Blackberry. The instant someone comes up with a draft standard for cross-platform push email and MS, Google, Nokia and Apple say they'll move to it, it'll be time to dump your RIM stock. Fast.
MS should be bloody terrified of LiMo and Android though, especially LiMo as like WinMo it doesn't have its Maker breathing down your neck all the time you use it. It's yours to f*** with as you wish. If MS don't maintain their OEM tie-ins they're going to be in the poo big time. The move of HTC to shipping Android units must have really stung.