I agree that the N800 needs a good PIM suite. The current N800 options really aren't usable when compared to Palm or Psion - I haven't used any WinCE based PDAs, but I imagine they integrate well with desktop PIM SW.

However, I wouldn't trust Nokia to come up with such an app on their own. They should be responsible for integrating it, but hopefully they would buy/license the product from someone else! (And hopefully it wouldn't be based on GPE...)

I also like the idea of having a local copy of the information on the device itself rather than depending 100% on the availability of a WiFi network. It's nice to be able to sync the device or to surf the web, but something like an address book should be completely contained in the device. (And it should be a decent address book to begin with, one that let's me define my own database format...)