See my 5-page review of the Easton EC90 XC carbon fiber wheelset.
Where I got my Easton EC90 XC wheels
I bought my set of the Easton EC90 XC wheelset at BikeBling.com., in Escondido, CA. BikeBling has a wide variety of cycling gear— give them a try.
BikeBling.com also has the Easton EC90 Carbon 29er wheelset, which amazingly is only 10% heavier than the 26" version.