OK... What does that mean for an average N900 user?
I setup a BT-DUN connection to the N900 on my Win XP Pro laptop for those times at the airport when I need more screen real estate than the N900 affords. For a single user, this is a great way to share an internet connection.
I'm planning on setting up my N800 as an in-car computer with OS2008 maps, Canola and Carman as the 3 anticipated usage scenarios.
Why not the N900 for in-car use? Simple. Screen Size! At arms length, the N800's screen makes manipulating buttons much more friendly.
In addition, on long trips, I can pass of my well used N800 to my passenger to surf while the shiny N900 sits in its cradle or jacket pocket (no selfishness there).
Interestingly, while a device is connected via BT-DUN, the N900 is able to maintain its own internet connection. Either the same connection as the tethered device, or a different one (wi-fi, for example). The screenshots below show that the N900 is connected to wi-fi while the N800 is tethered to it using the cellular data connection.
Figure 1: N900 IP while N800 is tethered (N900 on wi-fi and N800 on cellular data)
Figure 2: N800 IP while N800 is tethered (N900 on wi-fi and N800 on cellular data)