I believe that page is for Maemo 5 only. Yes, they're both Linux, but quite a lot has changed between Maemo 4 and 5, especially in the area of desktop widgets. At the moment there are more apps for Maemo 4 than for 5, but most of the new stuff will be Maemo 5 only, I'm afraid. Hopefully some developers will continue to update their Maemo 4 apps.

http://wiki.maemo.org/Mer is the closest you'll get to Maemo 5 on N8x0.