Now,this is cool if you do a lot of html parsing! You can tell I was drawn to it by the word "Agile" hidden in there. I guess "Agile" is the new black. It goes with everything.
HtmlAgilityPack is an open source project on CodePlex. It provides standard DOM APIs and XPath navigation -- even when the HTML is not well-formed!
The post is more specifically talking about use cases for this when doing custom validation and extraction of text while doing Web Testing with Team System, but I can see this used in many other places.