First version of IDEA Plugin Manager is done and will come in the nearest EAP build.
A Repository part ( http://plugins.intelling.net ) keeps plugin packages in JAR or ZIP format.
And another part is IDEA Plugin Manager component could be found in menu bar Tools | Plugin Manager.
It's just a first version and it can Install (download) plugins only :)
Plugins from intellij.org should be manually moved to plugins.intellij.net
It's free to add categories and modify category tree. And it's free to add plugins and it's updates.
Deleting plugins and categories is permitted.