I hated that concept too when I first switched to Xmonad, but after a few months I've come to appreciate that behavior. It allows me to keep one screen static while working on another.
This allows me to dedicate a workspace to communication (email, IM, etc), server, development, documentation, etc and move among them easily.
I've been using XMonad in a dual-monitor setup since I started working at Google in January... haven't had any problems with it. My general (rough) impression from walking around the New York office is that about one fifth of engineers here are using XMonad.
Really? I have not seen one other person that uses it. I haven't even heard it discussed, and I asked around a lot when I started. I'm surprised we have never discussed this, actually :)
Lurking along this thread (google engineer), this is exactly what I want for my multi monitor setup! Chrome on one screen, everything else on another, programmable WM to make organizing that other screen natural.
I don't know too much about the Linux desktop scene, and I'm plenty productive as-is, so I didn't even bother looking. Thanks!
So yeah, Google gives their developers plenty of control over their workstations :) And Xmonad rocks for productivity.