The first stable release of Abmho is out. It is by no means the first or only syntax highlighter on the web. There are quite a few out there but the vast majority aren't usable. Abmho can mix languages within the same code snippet, allows you to style your code with live preview and many more features. Perhaps one of the most interesting feature is that it is a silverlight application that runs both on the web and optionally installable as an OOB application.