In the past, KentBeck used "team" to mean "just the programmers". Separate from that group was the lone OnsiteCustomer. Now, it seems that he's getting benefits from thinking of the whole group as OneTeam. This also makes room for UsabilityEngineers and such. Here is the paper where he announced this change-of-mind:
http://groups.yahoo.com/group/extremeprogramming/files/One Team.doc
(Feel free to replace the above description with a better one.)