Andrew Eddie has written an article at SitePoint titled, Introducing Joomla. He writes a good article, although in this stage of the game I'm not sure why Joomla! needs introductions. Joomla! is a well known open source CMS in content management circles.
Joomla (TM) is among the most popular Open Source content management systems that exist today, in the company of Drupal and WordPress. If you just need to build a web site for yourself and are unfamiliar with all this HTML stuff, or you develop web sites for other people, or if you’re at the pointy end of developing web-based applications, then Joomla really should be on your evaluation list. It’s easy to install, use, and extend.
Personally, I found the comments to the article just as much if not more interesting than the article. While there has always been strong opinions about open source CMS, I've observed that there is becoming less middle ground these days. As you look at the comments you'll see opinions very strongly expressed for and against Joomla as well as other open source CMS. This trend of commenters only wanting to acknowledge the good or the bad in a CMS (or any product) has been troubling me lately...