These are two great recent talks about Agile UX. The first is by Johanna Kollmann, which presents findings from a research project that she participated in on this topic.
The importance of identity and vision to UX designers on agile projects
View more presentations from johanna kollmann.
The second is by Cennydd Bowles and is a great primer on Agile UX.
Getting Real About Agile Design
View more presentations from Cennydd.
Enjoy!