Thank you, Jason. But I must say it is a serious drawback, as I am in the verge of beginning my first real project in Revit MEP, and I will use oval ducts - how can I tell others in my company that this promising new software will not do what we want, and that's just starting... I think ABS would do it (now that's worse...) I really hope Revit MEP 2009 does it.
Thanks again for your reply.