According to an update on their site:

http://whitedenimmusic.com/white-d-tour-fall-2010

Not sure if the new guitarist is simply a touring inclusion or whether it's a permanent change to their set up.
Anyway, it sounds as though they've been busy: "We will have new music for you to hear and buy in October. It will be the latter of the 2 records we’ve made this year."

Exciting times!