I've started a project on drupal.org to contribute a module that will allow loading of new themes into Drupal from a compressed file (zip, gzip) that is either on your local hard drive, or from a web URL (curl support required?). View Project on drupal.org
It's a basic idea and I'm hoping to get some feedback from the Drupal community on how best to execute this. The idea came about when a friend of mine mentioned that he had introduced his brother (a Joomla user) to Drupal and got some feedback from him on what he thought Drupal was lacking.
The first thing mentioned was the weight system. Joomla uses a system similar to that which is implemented in the Views module where you can hit and up or down arrow to resort content. I heard mention that someone has been working on a module to do sortables with Drupal's new jQuery library, but it looks to be a 4.7 implementation so far.
I've not really seen much discussion on drupal.org about a theme installation interface, so I figure since it would help convert users and there is some good interest at least outside the drupal community, it may take some hold.
Update: Due to more commitments then I have time, I've discontinued any work on this module. My regrets.... read on