Is it possible to get the latest Unity without upgrading to 12.10 on my Ubuntu 12.04 PC or will this be backported?
Open Terminal, then type
sudo add-apt-repository ppa:benkai/precise-unity-backport sudo apt-get update sudo apt-get remove unity-lens-applications sudo apt-get install unity wget http://ppa.launchpad.net/benkai/precise-unity-backport/ubuntu/pool/main/u/unity-lens-applications/unity-lens-applications_6.4.0-0ubuntu2_i386.deb sudo dpkg -i unity-lens-applications_6.4.0-0ubuntu2_i386.deb
An official backport won't happen, no.
Because Unity 6.0 depends on the latest Quantal versions of Nux and Compiz, which in turn depend on the newer versions of other libraries, like libunity-webapps, indicators, etc. Unity 5.x, however, will continue to be supported for the entire life cycle of Ubuntu 12.04 with stable release upgrades to fix bugs.
It would be possible for a community developer to take the source code of Unity 6.0 and dependent libraries, try building it with Precise libraries (many modifications would be needed) and put it up in a PPA, but it won't be worth the effort.
I tried to give it a Google and found this link referring to Unity backporting from Quantal to Precise which may be of some use to you.