you need to add a hostname canonicalization redirect to your configuration.

if your canonical hostname is http://www.example.com then any requests for a non-canonical hostname (including IP addresses or example.com or foo.example.com or example.yourwebhost.com or https:, etc) must be redirected with a 301 status code to http://www.example.com

what type of server are you using?

This doesn't sound like a hostname. Or rather, not hostname alone.

IP/~username is indexed for some pages

Do you mean:
IP/~username/pagename.html
IP/~username/otherpage.html
IP/~username/thirdpage.html
?

Yuk. Can you still reach the pages that way? If so, you'll need a global redirect, something like (assuming Apache)

RewriteRule ^~username/(.*) http://www.example.com/$1 [R=301,L]

If the IP/~username form no longer works, you may prefer to let the server hand out a 404 and let everything die a natural death.

:: thinking that "temporal" is pretty funny, but the thread title should probably say "temporary" ::

Or rather, not hostname alone.

IP/~username is indexed for some pages

oops - i missed that part...

It's cool phranque, I thought you had the right answer too when I read your post, but Lucy24's got it -- Of course [guessing much like yours] my temporal lobe could be about ready to shut down right now, so I can barely even type, never-mind being able to talk [lol]

Mod's note: In deference to long term memory, I've changed the thread title from "Temporal URL indexed in Google" to "Temporary URL indexed in Google".