I developed an editor for OpenStreeMap (well not released), digged in navit source code, and have two year of experience as user and developer on my Openmoko freerunner.
After a lot of time we did not succeed to have a free turn by turn navigation system (several reasons). The problem is anyway maps data are not free or in open format, and that openstreetmap data are incomplete.

So actually the only way to have a free navigation system on the N900 is to get free ovi maps 3 on maemo5, or to hope that navit developers will have access to map format already freely downloadable for the device.

Well, why the problem? becouse when I go on the nokia site I see a big banner "With Ovi Maps free gps navigation system on your nokia" and that on the n900 there is *already* ovi maps.

So users just expect that a device that arrived only in these weeks on regular shops and that costs about 600 euros is on the list of supported devices (I have an old n70 too, but really I do not pretend to have ovi maps on it!)

Ok, it's not. Why? If this is a precise marketing line it's simply not acceptable. personally 600 euros for me is a lot of money, I'll skip maemo6, and may be I'll buy a new device (maemo7), and just want to be satisfied of my n900 for at least a couple of years.

But I really to not think this is the reality, and as posted before it's a technical problem, but even here I cannot guess why!
So just think nokia may decide to not use the man power to support maemo5, in this case please involve the community, I think that a lot of us may help in creating some sort of "framework compatibility layer".