If you are hosting your blog on wordpress.com and would like to post your source code, WordPress has a treat for you. Check out this Java code sniffet:
for (int i = 0; i < 10; i++) print("Line number %d\n", i); [/sourcecode]
If you are interested, check out this WordPress FAQ page. WordPress claims to support Python, but I have tried and the syntax-highlighting feature does not work.
Another alternative is to use the Code Colorizer which I have described in my previous post. The Code Colorizer supports a number of languages, but Python is not one of them. If you know a solution for Python, please post a comment here.