Thread moved to Plugin Exchange section of the forums for community based support/input.
Personally I'm not aware of anyone using such a plugin, but I know the request has come up before in the
feature requests forum, however ultimately with the introduction of the Vantage Theme we know it isn't something that will end up as part of ClassiPress.. When it is released however, you could always look at installating Vantage on a subdomain and linking from your CP install