Well, my N900 requires that I connect to PC suite and does a backup.
(BTW If I push the button "backup" (the only button besides "cancel"), then it does start the N900 backup. Doing that, or doing a PC Suite backup doesn't get to me to the next step of the actual update. Yes, I am gonna study the buglist for this firmware update. Grrrrrr)
im getting same message too, this is annoying because my friend got box asking "do you want to backup" and after he pressed no update continued, but i didnt have anything like that :[