PC Magazine has a quick article on Windows Home Server - something I've been testing out at home for a bit. I personally like it. The WiFi limitation is more based upon reliability of a link than anything else. WiFi still is not reliable (just do a search on 3945ABG & Vista - which is all Intel's issues). It's Windows 2003 Server underneath it all, which never was meant to be WiFi friendly - so drivers are always the issue.
The price is projected at about $500 - which is inline with what I would expect for the device - a price point that people consider the device as opposed to a full blown PC/Server.
There's more to Home Server than just network based files - auto backup & synchronization, etc.
Link to What You Can't Do With Windows Home Server - News and Analysis by PC Magazine