Nothing, of course, Ångstrom, Debian, and Ubuntu should install fairly easily (as can be seen with the Beagle Board hardware). The issue is that this isn't just like flashing a new version of Maemo. There'll be a fair amount of work involved (partitioning SD cards, setting up the bootloader, getting the correct kernel compiled, either installing x distro somehow or expanding a tarball onto a particular partition). None of these things sound like stuff somebody like Karel would be very interested in (he's been quite insistent on his non-technicality in the past), and I doubt many of the other people understand quite what's involved, either.

Now, don't get me wrong, I'll likely be getting myself a Pandora alongside the N900 (despite the sad fact that all and I'll be doing all sorts of stupid hacky stuff with it, but that's me. Not everybody has the time or interest to play around like that.

In summary, those looking for a very consumer-friendly package should look elsewhere.

Well, for the PowerVR at least, the Beagle (which runs an identical OMAP3530) is getting drivers around November, so there shouldn't be any issues with using those for other distributions.