This is not officialy supported to run LiveCycle ES/ES2 on any linux distribution but Enterprise Red Hat or SUSE Linux. But this does not mean this is not gonna run on Ubuntu.
I've tested LiveCycle ES2 using Glassfish and Geronimo as application servers, that are not officially suported, and that works.
For testing/developing purposes, i think you may use Ubuntu, but if you run in troubles you wont get support from Adobe.
Do not try any unsupported platform for production environments.
