Cost will be the big question. With the RS21 gadgeteer module at $100, and even bare WiFi modules at $30-$50, the expense of building a sensor network over WiFi can get overwhelming quickly.
The competition is things like Nordic’s offerings, which work for lots of these short-range in-home applications and can be had off of eBay for <$10 per module (in hobbyist-friendly packages).
It would get VERY interesting if Qualcomm/Atheros could compete on this level. Integrated IPv4/IPv6 stack is definitely very nice.
Looks like Freescale is selling a development board for $70.