802.1x IPHONE and IPAD

I have a customer asking the following question; 
   We would like to know if anyone has any experence with the following:
   They are running a RFS7000 with Wing 4.3   Doing 802.1x with internal Radius to an external AD.

Can you verify with other customers if any that are currently using iPhones/iPads in their enterprise?  How are they authenticating against Web/SharePoint servers? 

He got his IPHONES to connect but everytime he switches SharePoint servers it wants a new login.