You should ask this on the EJB3 (dev) forum.
They are already using MC to some extent,
but I have no idea how much that helps wrt hot deploy.
I know JavaRebel has a support for the new MC ClassLoading layer,
perhaps that could already help.
And afaik writing a plugin is not that difficult, I know Spring has one,
hence it would probably be easy to add one for Seam as well.
created Oct 07 and still unassigned. Obviously not a priority (not mandated by EJB3 spec). I posted and voted on this JIRA.
I emailed the JSR318 group regarding this. This needs to be part of a future EJB spec (i.e. required for JEE middleware implementations).