Setting up continuous integration for a single project can be a pretty daunting task. Doing that for hundreds of projects becomes a challenge of a different magnitude. Not only are their capacity problems, but some tests are destructive to the testing environment, some have esoteric environment demands. See how this is solved in the real world using Jenkins, jclouds, CloudStack to build an on-demand build infrastructure.
About David Nalley
David Nalley is the Vice President, Infrastructure at the Apache Software Foundation and a CloudStack PMC member.