I see what you mean, but if that is the case that the testing and regression procedures is what takes so much time, then Nokia could have made very good use of the community by using release candidates. Look what happened with the leaked one. It didn't take long until the community had reported a lot of pros and cons and odd behaviours with that version. they should make use of the open software concept as far as possible I think. Then of course, if some parts of the closed code actually contains some trade secrets then I understand why it could be sensitive to release it prematurely, its also a matter of trust in their products as a whole. If they would have released untested crap after crap after crap, there would not really be any improvement of the confidence in their products in general.
Guess they have to move with a little care even if its partly an open source product, or perhaps even especially careful in such case. It's a somewhat tricky question I suppose, but indeed Nokia should have been better with information to the public and customers. As it is now, it is just a bit too silent. What is actually irritating is that there doesn't seem to be any separation of bug and feature releases whatsoever. One may wonder how they are thinking there, the public patience could have been much better if they now and then were fed with some cumulative fixes, at least for the bugs that's possible to fix that way without performing a full upgrade.

But then again, I have to repeat it here: Personally I do love my N900, and I wouldn't trade it with any other smartphone/internet tablet out there. In fact, there is none as far as I know.