Hello,
I use Arduino for 2 years now and want to convert to FEZ as I am fascinated by programming possibilities and program stability. Because money counts, I need to know if I can use following arduino shields with FEZ:
Ethernet is officially and professionally supported by GHI, Yes.
As for that wifi board you pointed out, it will be a very bad option for NETMF, the community + GHI are looking for the best option. You an of course connect any serial <->wifi module and get it to work if you know what you are doing but we are looking for something we officially support so you would never have problems.
If you are desperate for Wifi support now, you could always hook up a wireless bridge device. They add bridge device like this [url]http://www.amazon.com/Cisco-Linksys-WGA54AG-Game-Adapter-802-11A/dp/B0006OCZHG[/url] I have used them in the past and they can give any wired ethernet device wireless capability. (This assumes you already have the Ethernet shield.)