From Jeremy Crabtree's comments in the Moodle forums: "I think it would help people form a more accurate mental model of plugin installation and removal if there were a better defined, explicit interface for installing and uninstalling plugins, modules, blocks, etc."

During the upgrade to v1.9, there is a plugins table that lists all the standard and non-standard plugins on the system. Perhaps this table could be extended to include install/upgrade/uninstall links, then accessible via a link in the Admin tools.

The original forum discussion can be found at: http://moodle.org/mod/forum/discuss.php?d=92558