UPDATE - I found this proposal over on area51. It suggests a StackExchange site for Windows Mobile. Go follow it if you want to see this!
I've been using a computer like this at work for the last few months.
This stand alone computer is complete system that has the ability to access the internet via IE over WiFi, edit documents via Word, and so forth.
It doesn't have the ability to make phone calls, send SMS messages, or any other phone-related things unless a VoIP softphone program were to be installed (like Skype on a desktop).
I could be wrong, but to me this machine counts as a "computer" according to the SU FAQ.
Are questions about mobile computers like this on topic? I couldn't find another SE site that was tailored to such machines.