This is a Syntax Highlighter plugin for meant to be used with the new Blog4Umbraco package.
This will highlight any code written in a <pre> tag like this:
public void test()
string test = "test";
This is a one-click-install on any site that has a <head runat="server"> element. If not, then you will need to insert them macro manually in your <head> element.
Let me know how it works for you :-)