Dreamhost announced A Fistful Of One-Click Upgrades
The following software can be upgraded through OneClick facility.
* ZenCart 1.3.8
* Pligg 9.9.0
* Moodle 1.9
* Joomla 1.5.1
* MediaWiki 1.12.0
Dreamhost also said, WordPress 2.5 is testing and will be available later.