Funny thing is Nokia was the first with real internet tablets. They were not able to define the tablet space and make it mainstream. Although the software was good enough ( I guess. Unless it was much worse than N900/ Maemo 5. I have no experience with any Maemo device prior to N900).
And right when they admitted their failure to make the tablet space big and pulled out of the tablet market by making the next tablet a phone sized device (N900), Apple launched their tablet and created a huge tablet market. And now everybody is following Apple's "lead".

Why didn't Nokia release a bigger 7" or 10 " tablet in the last 1.5 year?
Isn't Maemo 5 good enough for a tablet? It is certainly better than iOS. And you can run all of the thousands of linux applications out of the box. No need to adjust UI.
They could have had that market, or at least be the second biggest in that market which is also a lot if you see how few Android tablets have had succes in the past 18 months.