Well, I finally had a chance to perform the upgrade last night. I used Ubuntu for the flashing and it went very smooth. But I can see how this would be quite intimidating for newbies or non-techies.

For those that are a bit afraid to take the plunge, I would say go for it. If you have any questions do not be afraid to ask. You can use this thread if you want. The basic steps are the following:

• Perform a backup.
• Download the firmware file from here: http://tablets-dev.nokia.com/nokia_N900.php (You only need one file.)
• Use the link on that page to download the flasher program. As I said I used the Ubuntu option and it was a piece of cake.
• Follow these instructions: http://wiki.maemo.org/Updating_the_tablet_firmware
• After the update, reboot and restore your backup. It will offer to re-install all of your previous apps. That means that you will need an active Internet connection during all that. It even puts back the icons to their previous locations on each different virtual desktop.
• Do one more reboot and you are done.

Hope this helps.