A few people (this means you Vahe) had noticed that planet.perl was formatted funnily. The reason - HTML truncation in some of our inbound feeds. I.e. the RSS would include the opening <ul> but not the closing </ul>. This could cause odd indentation further down the page.
A not-so-well-kept secret is that planet.perl is based on a Python tool called planet. So, while watching an episode of the PowerPuff Girls, I subclassed HTMLParser and wrote the utility to add missing closing tags, where appropriate. The code is stupid, but tiny and crystal clear.
One thing Python generally gets right -- it is trivial to subclass its core modules.
Result? No more weird indentation! At least until even odder broken HTML comes in....