Temporary address like Google Apps?

One of the nice features of google apps is that they provide a temporary address when you are migrating from your existing provider. Is there anything similar to this in DH? I need to set up forwarding accounts for a client. Can you create domain aliases like google apps does? For example:

This provides overlap until the mx records are switched over and ensures no messages fall through the cracks. Can anyone point me in the right direction?

You can use dreamhosters.com aliases for websites, but not mail:
http://wiki.dreamhost.com/DNS_-_Viewing_site_before_DNS_change

The best thing I can recommend for no mail loss is to forward old addresses to a third party address.

-Scott