I have just changed our whole IP range on win2008 R2 network (win7 sp1 clients) which involved creating new DNS zones. I deleted all existing records on the old range (which in hindsight I think I should have left) and now see the new client IP's populating the forward lookup zones from DHCP.
The Q is that the reverse lookup zones dont seem to be populated. I have got the settings below ticked:
In Forward lookup zone record - 'Update assiciated pointer record'
In DHCP - 'Always dynamically update DNS A and PTR records'