The 300 Nokia N900 devices we loaned in the Maemo Summit include software release from early October. This software cannot be updated with Nokia Software Update (NSU) even if NSU identifies the software we are shipping now i.e. 42-11.
This is due to updates in the lower software stack in the pre-production models.
Nokia-N900-42-11:~# uname -a Linux Nokia-N900-42-11 2.6.28-omap1 #1 PREEMPT Wed Oct 28 15:32:55 EET 2009 armv7l unknown