It looks like the frequency's are different but I am confused

Why didn't you post any links in case you have found any information you don't understand?

But two important things: A phone as to follow all regulatory requirements for a market. Which means that it must use only frequencies allowed in a specific country - even if not required to support all frequencies.

And T-Mobile must obviously also follow regulatory requirements - only use frequencies allowed in the country even if they may decide to skip one or more bands.

But in the end, it would be very surprising if the phone only supports one allowed frequency band and T-Mobile only supports a different allowed frequency band.

Apparently you're talking about T-Mobile USA (T-Mobile originally is German). There are different frequency bands for 3G in use in the US.
The frequency band that T-Mobile uses is the one that's most widely used around the world. So it's very unlikely that the N9 will not support this frequency band as this would render the phone practically useless for 3G around the world.

It's the N9 supposed to be penta-band? It should support 850MHz UMTS as well as 1700MHz AWS, and if that's the case, T-Mobile USA will work fine for 3G service.

first of all please provide the source from where you read about the 3G bands available in N9, as far as I know no body knows anything about it until now. Everything you read around is just pure speculation.

First of all, no.

And you clearly don't know very "far" if all you can say is "everything you read is pure speculation".

I just read on various sites and compared it to the N900 frequency and they looked different. I remember having the N97 and I wasn't able to have 3G.

Also why couldn't Nokia merge the N8's camera into the N9's? It would be a super beast phone.

Asking why nokia can't do this or wont do that is slly, when noody knows if N9 even exists.

Gotta love GSM Arena.

N9 [speculative] http://www.gsmarena.com/nokia_n9-3398.php

N900 http://www.gsmarena.com/nokia_n900-2917.php