Integrating a Linux desktop into Active Directory is one of the dreams of nearly any Linux admin. The simple fact of the matter is that AD is a very good product and has won in the marketplace. Just hooking up your Linux clients and having them authenticate against AD is not hard, and the ubuntu-directory team is making it easier. However, this is only part of the puzzle. As Jorge Castro said to me, "I would kill to be to control the settings on my Ubuntu clients from AD".
Jorge, start your murdering. Today, Enabled People, makers of Linux-XP, showcased their "Integration Service", which purports to show the controlling of gconf lockdown via AD policy. Interesting, but no code yet, let alone a license the code will be under. We can only dream...