This is an extract from this blog post
If your site remains very active, we’d
love to work with you to migrate it to
the new, community-owned Stack
Exchange platform. That would be the
best thing that could happen to a
Stack Exchange 1.0 site, in our
opinion: that way your site can take
advantage of our existing resources
and expansive community.
So in a word yes; providing that you are receiving enough traffic for it to be a viable option.
I would imagine that it would have to come under StackExchange control & domain naming, unless it becomes a special case like http://askubuntu.com
Normally, I would suggest that you create a proposal on Area51 but as this would be a migration and not a new site it would probably be best to wait for a concrete response from a member of the Stack Overflow team.