Yup. The idea was/is to "stop bme" and then make your N900 consume as little power as possible (offline, nothing running, etc.). Supposedly you get a couple of seconds to swap batteries.

Although I cannot prove it anymore in one of my many attempts at unbricking one of my N900s (see around http://talk.maemo.org/showpost.php?p...&postcount=450) I could easily turn on my N900 being plugged but without battery and type stuff at the U-boot console and (attempt to) boot the kernel.

I'm talking MANY seconds, not 1 or 2. Obviously this may (or may not) have had an impact in my failure to unbrick it. Probably the poor thing was in some electrostatic limbo (after leaving it rest a few months I successfully unbricked it..)