Marketshare is indeed important but it doesn't necessarily relate to the biggest profit.
The earlier posted chart showed Sony dominating marketshare of home consoles but no where near Nintendo in profit.
Same with phones, RIM and Apple between hold 2-3% of all phones sold yet between them account for almost 45% of all profits made from the industry. 20% to apple.
Should Apple and RIM move up to a tiny 5% marketshare they will make more profit than nokia even if nokia had 50%.
Someone mentioned MS cracked the gaming industry with the xbox so why not the phone industry.
The phone industry is not a three horse race. There are a hell of a lot of major players out there.
The rumoured zune phone? If it is running WM7 then what's the point. MS will be competing with companies already lincensed to use their windows software and with a lot more experience in the industry. What can the zune phone bring that a samsung\LG windows windows phone can't?
Damn near any phone manufacturer can buy the rights for windows mobile.
MS releasing a phone is similar to them releasing a laptop to compete with dell and HP.
RIM and Apple phone software runs only on RIM or Apple devices.
I like android but I won an iphone 3gs and the apps is what gives it the edge over everything else out there, if you are into that kind of thing.