Obviously most of us do not use N900 as phone
Otherwise probably the list with the essential updates would start with:
1. Add group support for contacts
2. Add personal ring tone for contacts
3. Add a decent MMS support
4. Add more fields for contact's details like middle name, prefix, spouse etc.
4. Add video conference support
etc. etc....
... things that are supported even in the most simple Nokia phone models...

And the problem is not with which update by Nokia we will get these, but why a phone promoted as a bussiness one, doesn't have them by default in the first place.
If I were you, i would have more patience for getting the features you miss... and i wouldn't count on Nokia introducing those, but on the maemo community
BTW Have you seen a free talking OVI maps app?... I think first they have to use more up to date maps, especially for smaller countries
As for Skype videocalls... ask Skype developers...

Just be happy you got a phone with great hardware and a great OS that has a great community supporting it...
And Nokia... well i prefer not saying anything... 'cause if it was not for the hardware bundled with a unix OS, i would never bought anything from them...