I don't think most people 'get' the real reason to own a N900. Hardware matters of course, yes, but putting all hardware comparisons and issues aside for a moment, it's really all about the OS! Nothing else - not Android, Symbian, WinMo, whatever - puts a real desktop-type OS in your friggin' pocket. Especially an open, root-enabled one that lets you do what you want without a jailbreak of some kind.
Everything else - Symbian, OS-X, WinMo - they're designed to be just smartphone OS, and closed at that (ok, Android is kinda open, and Symbian now is open). Nothing else is as capable as Maemo/MeeGo, which was designed from the start as a real pocket computer OS, powerful and flexible enough for whatever the future brings and with the promise of cross-platform compatibility for apps through Qt, which is also open.
So no, I would not trade my N900 for anything now available. I bought it because of Maemo and nothing else has it. I'll keep my N900 until some better hardware comes along. But whatever eventually replaces it, it must run some flavor of linux - such as MeeGo or similar - and so be an open OS.
And no, it will not be Android - no chance, been there, done that, won't get fooled again.
Yes, the one out now would be the Sony Ericsson X10 I think and coning out will be the unbelievably powerful and super loaded HTC EVO 4G!!!! Have you seen the specs?! It's awesome! I recommend doing a search on Google for a review and YouTube, Definitely getting one when it's out.
N900 has been quite good for a few months, probably the best option out there, but it is a bit buggy still, the dedication by Nokia is not present and they do not listen to what the vast majority of owners want. i,e No mms (a basic option on the most basic of phones), no video call despite the redundant front facing camera, no portrait mode (my windows MDA Vario had this years ago), it's very heavy and thick.
It's a very good phone, alright tablet with a phone bit added! lol, but if it does both, do them both well.
Unfortunately there are other manufacturers that want my money and are offering all that the N900 does and a lot more!