Notice that I own a G1 (converted into ADP), so I have some pro-Android bias.
> One interesting difference is that N900 is the main product, while Android Developer Phone is just that, a side product. In general one cannot select any Android phone from the market because of the limitations, instead having to trust there will be sensible... no, even cool dev phones from Google.
I think you nailed it here. Nokia produces both the software, and the hardware of the N900. Google only does the software. So the ADP, *promoted* by Google and actually produced by HTC, have this aspect of "secondary" product to it (and it sucks).
The G1/ADP hardware has now the advantage that so many people bought it, that it is very well supported by the community. So the "side product" issue was mitigated, but it is uncertain how we are going to have well supported recovery images when the Android FOSS-fans user base becomes fragmented into many different handsets. Nokia could win big time here.
I am curious about how well integrated and easy to use will be the N900. My wife has a Nokia smartphone, and I find it *very* poorly executed in some places. Nokia didn't even release this new Maemo, and (if I got it right) its API is already marked as deprecated.