I'd like to introduce good tool helping to administer multiple wordpress sites at one place - wp-fox
This utility is all-in-one tool for sites management.
- upgrade all plugins by a click
- upgrade several wordpress by a click
- install a plugin/theme to several blogs at once
- setup new wordpress on your hosting without need to have any other tool (like ftp client, etc)
Manage users, posts, pages.
See details at http://wp-fox.com