A Wordpress Upgrade Guide
Anil Dash has an interesting upgrade guide for Wordpress. I think this is only deserved, after the upgrade path opportunity that Wordpress used during the MT3 licence debacle.
P.S. tense twittering between Matt Wullenweg and Anil Dash. I think Anil is right here, and I cannot find anything in his original post that is wrong and even less desperate, it's a fair shot at competition.