People got the other Maemo devices booting to other Linux distributions. As Stskeeps mentioned, it took a lot of hacking to get it working, and things just never got quite right.

I personally think the "Easy Debian" route is the best one for the N900 for the simple reason that people want to keep using it like a phone, and they're not going to want to lose that functionality when they leave Maemo.

So this means one of three approaches:

• Run apps from different distributions right in the Maemo environment. This seems to be a bit of a disaster, as the window manager mangles the dialogs and widgets pretty badly.
• Close down Hildon / Matchbox, start your own desktop environment (like Penguinbait's KDE, or my replacement-LXDE) -- I haven't heard if this works yet. You want to keep the telephony stack running, and it may not be stable in other desktop environments. Looking forward to the first reports from hackers in the next weeks as the DDP devices finally start arriving to our Hacker Team
• Run a secondary desktop environment on top of Maemo. Again the window manager hinders us! The Xephyr nested X-Server, which I used on previous devices to show a secondary desktop, doesn't grab the keyboard properly due to the WM's non-standard way of giving input focus to windows! Argh!

So, the only way I've found to get a secondary environment is to use vncserver in the Debian environment, and the Maemo vncviewer to view the WM.

Needless to say, I'm pretty frustrated at the moment.