Today I got the time to upgrade the WordPress MU platform which is running the Valsania Corporate Blogs collection from version 1.5.1 to the release 2.6 (which is based on WordPress 2.6). It has been the first time I upgrade a WPMU instance in a production envirnoment. The upgrade procedure has been extremely straightforward, and I must say I’m quite impressed by that, since my WPMU configuration is very complex (many plugins and customizations were made, but all of them should have been made consistently with the architecture). At the same time I got all the others WP-based blogs I manage upgraded to the 2.6.1 release.