If you're impatient, you should probably get a 4g. It will be awhile until the 5g is released, since Apple is doing the iPhone 4S right now and it will be another year until the iPhone 5.
Wait for the new one, trust me. An iPod Usually Lasts 2 IOS Upgrade, ie iPod Touch 2g can upgrade to IOS 3 and IOS 4 but not IOS 5, so the iPod touch 5th gen will probably Last For IOS 6 and IOS 7
also there are probably chances of a better camera and faster CPU and might come in white if youre interested
Just wait for the new iPod Touch. I mean, why would you want to upgrade to a 4th Gen when the 5th Gen is coming out soon? If you can't wait, then might as well go with the 4th Gen. Everyone's already thinking, new CPU, new camera, etc; on the next gen iPod Touch.