I really like the upgrade feature of wordpress. It is impressive how smooth it is to upgrade wordpress. Just click a button and it is upgraded. The same is true for plugins.
This is something that other webapplications can learn from. It is probably not easy to implement, but makes is much easier for users to use the system.
Upgrade to WordPress 2.7
I have just upgraded to wordpress 2.7 and applied a new theme. I like the upgrade procedure, eventhough I deleted to many files and the theme. I would like my products to be just as easy to upgrade.
I like the new design, and hope to use it a little more.