Any self-respecting coder will not blog about programming without proper code syntax-highlighting. If you use Blogger, I'll save you the trouble of googling... Good results here and here.
As mentioned in the above blog links, I too am using TextMate on OS X which has a nifty built-in 'export to HTML' which, when combined with TextMate's themed CSS, gives very nice looking code blocks. You simply select the code you want highlighted, export it from TextMate, and paste into the HTML editor in Blogger.
I saved the TextMate CSS into my blogger template, so now any <pre> tag will produce a pretty code block, and any pasted HTML code from TextMate will be blocked and colorized.