Continuous integration is a fairly simple thing: detect a new source commit, run a battery of tests on it, report back. Hudson is a really good one (of which the original author is a main contributor, and I did some plugin work for a while), and I use it as a fairly fancy looking cron as well.

Continuous deployment, as described in the article, is much more difficult. Not only do you have the slew of tests, but maybe you want more long-running tests that you don't care to run all the time. Maybe you want code reviews. You'll need to automate the actual deployment process and so on.