One of the more interesting points in Evhead's new colophon is the xml backend (interesting for me, anyway. Shut up). I've discovered that xml parsing in php is considerably faster than in Perl. So much faster, in fact, that it's actually useful. With that in mind, I'm looking for an xml weblog schema. Evhead's xml has the right balance of nested tags and tag attributes for me -- and Blogger have an xml and asp howto that covers the xml in a little more depth.
To be honest, what's going to take the time is making sure all the old archive links and permalinks still work and that there are no visible changes to the front end. Iterative change, that's what I like. And geeky stuff. And techno. And a good chicken pie. Mmm. And cheese, oh yes, let's not forget cheese. A good Canadian cheddar gets you a long way towards perfection.