Part of my reason for doing so is because I really miss talking politics and hanging out.
The other part of my reason is because I like the idea of a group that sees itself as moderate (though this may turn out to not be reality). Even more, regardless of whether it is moderate or not, its mission is to create a place for CIVIL discussion. This alone would make me want to join any group, liberal or conservative.
Anyway, here is there website. I think this is the official one, although others are sprouting everywhere.