EDIT: Please see this post below, which gives more complete instructions.

yeah you're right. Sorry.

You may be able to still use the instructions located at http://sse2.net/rotate/ with the following debs:

kernel-diablo-flasher_2.6.21-200842maemo1rotationfast_all.deb and xserver-xomap_1.3.99.0~git20070321-0osso20083801rotation_armel.deb

It has been suggested below that to take the place of downloading and installing osso-software-version-rx34-unlocked_1%3a5.2008.43-7_all.deb, you should gain root and then enter the following in xterm (for n800)

or (for the n810)

According to this, you may need to enable maemo-extras-devel in order to use apt-get install osso-software... But please be careful: if you enable extras-devel, make sure you disable it immediately after use apt-get install to grab osso-software-version. Otherwise, you may be fooled into using not-ready-for-prime-time debs to update your favorite apps, thereby loosing functionality and f-ing up your whole device. Seriously, be careful with extras-devel.

Note: These debs will work only until the next ssu (if that ever comes). At that point we'll need qwerty12 to vouchsafe some new debs.