WinMo is bad right now. But Windows Mobile 7 is supposed to be great. The Zune OS is very good and will probably influence WinMo 7. And let's not forget Microsoft was already late once to the party with the PocketPC (Windows Mobile 3.0) and still nearly crushed Palm with its Palm OS.

RIM is at a difficult point. Will the stay focused on the business phones or will the expand even further into the multi media phone market? But I would say they are here to stay.

WebOS... hmm, could go either way.

Symbian, Symbian^1 (current) is done, there are no more bunnys that can be pulled out the hat. I think S60 5th editon is as far as it can go, but Symbian^2 could be good. So I would say Symbian will be around for a while. If only on 'dumb' phones.

Android. A big yes, I don't have to like it, but it will be there. There are a few obstacles in its way, multitouch in the US or speed to name two, but nothing that could not be fixed (see Droid). Plus Google, nuff said.

Moblin as mobile OS, I just do not see that.

iPhone OS, (OSX Mobile). Can you really take over the world with just one phone? I don't think so. I do not want to see everyone around me using the same phone. (two colors don't count as different, neither does the 3g vs. 3GS) I want a pink slider phone, that glows in the dark and can be worn as belly piercing on the weekend... (Ok I don't want that phone, but someone does...)

Here comes the problem, I think there is only room for 4 different mobile OSes. I named already seven, so what about Maemo?

I think it will be hard. Don't get me wrong, I ordered a N900, I own an N800 and I think it is great.
But there is hope, if Nokia really can provide a developmet plattform (with QT) that is identical on Symbian and Maemo, I think Maemo has a chance.