I just caught an interesting article on managine offshore XP teams in
the Agile Journal by Peter Vaihansky

The essence of Extreme Programming (XP) is making the customer a part
of the team who works very closely with the developers, ideally
communicating on a daily basis. However, what about a situation where
your development team is offshore? Is it possible to have the best of
both worlds, realizing the gains of offshoring without losing the
benefits of XP? How do you keep the momentum and the communication flow
going, at the same time ensuring seamless integration of the
deliverables into the customer's production environment at the XP pace?
This article will cover four years of cooperation between StarSoft and
one of its major customers, a leading computer chip manufacturer. In
this period of time, StarSoft has delivered 61 successful projects to
the customer, with five more currently in development, utilizing XP
exclusively. We will discuss the organizational model, roles, and
responsibilities used in this highly successful relationship, as well
as the tools used to monitor and manage the projects daily.

I think its worth a read.
http://www.agilejournal.com/content/view/108/43/