It was a pretty trivial pipe I created to grab my LiveJournal RSS feed, filter out everything without the "python" keyword, and serve the result. Only one hitch. It seems Yahoo! Pipes mangles whitespace inside pre tags. Oh dear. So basically any code I try to post will get mangled by the pipe and be more or less unreadable.
Yahoo knows about this problem (people have been complaining about it for years). Bummer. There's a post in their suggestions forum about the problem that's a year old: