OpenStack Essex is the version of OpenStack being placed on the current LTS of Ubuntu, but it doesn't include Quantum which has some great networking improvements for OpenStack. This is coming in the Folsom version, but 12.04 currently has Essex. What is an admin wanting folsum and LTS to do in the mean time?
From Canonical whitepaper "What's New Ubuntu Server 12.04 LTS"
So if you use Ubuntu Cloud Archive yes, Folsom and other OpenStack releases will be available to LTS.
More info about Ubuntu Cloud Archive can be found here: https://wiki.ubuntu.com/ServerTeam/CloudArchive
and according to this page, the archive isn't up and running yet, but is nearly complete. https://blueprints.launchpad.net/ubuntu/+spec/servercloud-q-cloud-archive