Minus one minor problem with an outdated WP-DownloadManager plugin, upgrading to WordPress 2.6 was relatively painless. The aforementioned plugin, which I use for managing the theme downloads here at Theme Lab, was updated by the author – correcting the bug. Here are a couple articles with tips on upgrading your own WordPress install:

You should always be taking regular backups of all your sites, especially in preparation for something like a software upgrade.

I’d like to know how your WordPress upgrade went. Any issues?