Following stackoverflow's example, I've started using prettify for syntax highlighting on this blog. I've used the Google syntax highlighter in the past, but prettify just seems easier as I don't need to mark it with class names or anything - all I need to do is wrap code in <pre> and <code> tags, and it just works. It's clever enough to work out the language.
Getting it working was really simple. I downloaded the source, combined all the .js files into one using Google's Closure Compiler, and update the .css file to the styles I like (stolen without shame from stackoverflow - I love that site).
To get the styles to apply to my blog, I also added an initialisation script to make the prettify call, and it works. Hopefully this should save me some time in the future.
I found a really good article here that showed me how to set this all up. I'll update old blog posts at some stage, for now they're going to appear without styling.