This post is long over-due and I really apologize for that.
Some months ago we put out the call for "more slave machines!" through the mailing lists, sky-writers and twitter. We had a serious problem, for a continuous integration project, a large number of our plugins and dependencies weren't being built in a continuous and automated fashion!
We had some builds on a couple of flakey machines on home connections contributed by various individuals, until Rackspace stepped up in a big way and donated an infrastructure server for the project to use.
For months now, just about all plugins and core have been built and tested on
the always-on machine in the Rackspace Cloud. Dutifully chugging away building
core, plugin after plugin and occasionally getting flooded with work from Frederic
Camblor's plugin compatibility tester!
In hindsight, having a powerful infrastructure machine for nothing other than builds has helped us build great software faster; I can't imagine how difficult things might be otherwise.
I've personally had a lot of interaction with Rackspace engineers through the OpenStack project and have a number of friends who operate businesses on Rackspace/Rackspace Cloud hybrid infrastructures.
The folks at Rackspace are top notch and I can't thank them enough for contributing to the Jenkins project.