I have an N900 with regular + latest power kernel.
With either whilst the kernel boots, after the flashing dots and nokia logo, not desktop appears and the device "appears" hung.
nitdroid V12 boots fine, and from there I can access the maemo filesystem :-)

Whilst I'm very familiar with linux, I am less so with maemo itself -- need to poke around for log files etc to figure out why the desktop doesn't start. I have a feeling perhaps the khweeteur experimental app installed something into bootup (as it was popping up errors when maemo was booted - before I decided to remove it).

Nothing obvious in startup yet, so suggestions welcome to
- pause the boot at an appropriate time and start rest of startup manually (switching default runlevel perhaps?)
- identifying relevant logs to determine cause of failure

I'm perfectly ok doing a reflash (done it many times....) just intrigued...