I'm not sure what would be involved with setting up email alias support, but that would be a great enhancement.

The feature that is on SourceForge:
"Each user is provided with an email alias in the form username@users.sourceforge.net. This mail alias forwards email to the email address on-file for your user account. This email address is provided during the user account registration process, or through an update via the Account Maintenance page."
http://sourceforge.net/docman/display_doc.php?docid=6693&group_id=1#user_alias

Anyone know what would be required for this code wise and server side?

my guess is that sourceforge create a fwd account on the server itself, when a user registers..

i don't think it's as simple as u think.. and i doubt you'd be able to do it on a shared server, or if you could, then your host provider may put limits on it if your site is busy..

Oh, I know it isn't as simple as it sounds :)

I've been tying to find info on how this even works (what all is needed on the server side, scripts, etc).

Agreed, it would require a dedicated server.