I've been tossing around the same idea, and from what I can tell, you're looking at three things to be configured in order for Linux and Active Directory to play nice. You need Kerberos, LDAP, and Samba. AD needs to be tweaked a little bit, since Microsoft has added quite a few proprietary features to their implimentation of LDAP, as well as Kerberos. You're also going to need Samba to communicate between the Linux portion of your network and the AD portion. The idea in this case is to get the Linux and Windows machines to authenticate via the AD domain, using Kerberos and Samba, and to use something like OpenLDAP as your preferred directory service for the Linux machines, in order to match up with Microsoft's LDAP implimentation in AD.
Since I'm fairly new to Linux, in comparison to my Windows experience, I'm still learning all of this as I go. I can, however point you in the direction of a good book to pick up if you're interested in making some of these scenarios work. Linux in a Windows World
by O'Reilly Press is a very good reference to get an idea of what you need to create a truly integrated Windows/Linux network environment. Like I said, it has a lot to do with installing the proper services on Linux, and tweaking the standardized features of AD, in order to create a network that can communicate with the least amount of fuss.