Good question and at this point I don't have an answer for you. I was working on the group code last night and changing the way it gathers the groups. The new way it returns the groups does have the domain name as part of it (returns as DOMAIN\Group) which if I left it like that you'd be good to go (I haven't tested this but you should be able to name a DNN group DOMAIN\Group). However there are x number of other installations out there that just have the group name and it's unrealistic to ask everybody to change the name of their groups to match that format.

I haven't implemented the change yet (next task after answering forum posts) but I'm thinking I'll check to see if a group exists in the Domain\Group format and if it does then add the user to that group. If it doesn't then I'll trim the "Domain\" section off and check for that group. That should do the trick I think.

EDIT: I have to take back what I said. Yes you can create Domain\Group roles in DNN but, unfortunately, the current AD search code doesn't like to search for groups in that format. I'll have to look at the search code next week to see if I can find a better way.