First let me say that Linode so far has been pretty great. Having a fully featured Gentoo machine is not an easy thing to find. I know I am not the only one who is here because they love Gentoo, so I think we would all appreciate one little thing, if it doesn't already exist.

Since there are certainly many Gentoo installations all in the same datacenter, wouldn't it make sense for them all to have the ability to sync to a local rsync server with the Portage tree available? This would certainly save tons of bandwidth and should require minimal resources to set up.

The bandwidth savings could be taken to another level with a full package file mirror, but this would require quite a bit more storage. Still I think it warrants thinking about.

Any chance of this being implemented, or does it already exist?

They don't have repositories for much more popular distros, why would they get a niche one like gentoo?

That's precisely what I was thinking. Check out the stats:
http://www.linode.com/about/

I'm pretty sure Ubuntu and Debian users consume way more traffic for updates in total at Linode than any type of "emerging" the Gentoo users do.

If you're in Newark, you can sync with my node which replicates portage every night. PM me with your LAN IP and I'll give you access.