It will be great to have Recovery mode for n900. This mode should be similar to most Linux destributives. It is actual at least this question was asked on forum 3 times in last 2 days. Errors in some files (for example "/etc/event.d/rcS-late") can brick device. Even users know where is error, they cannot fix it. Thread for discussion can be used this: http://talk.maemo.org/showthread.php?p=450655
Additionally this mode could be usefull for perform fsck on unmounted /home partition