I know it exists, have gotten it working with one of those AD compatible samba based DCs before, but not without some messing about. I'd really like to see it as simple as it is in Windows before saying it's a drop in replacement.
Tried the other day with Mint and ran into something where one of the searches promoted manually editing the hosts file to point to the DC and Kerberos address. That kind of thing shouldn't be required and is the kind of buggery I'd like to see sorted out.