This trac ticket has been tagged for 3.4 which is quite a while away from happening. Basically, the current way multisite handles images on the sub sites, is by running every request through a file called ms-files.php. This can actually be overridden via the sunrise.php file. The proposed change would involve moving new sub site [...]
Testers, start your engines
The bulk of the merge has been done in WordPress core. At least with regards to moving over the files. Now the fun part begins: bug gardening, testing and tweaking. Here’s what you can do to help not only the dev team and others, but also yourself: – set up a local install of WPMU [...]
2.9 status
WordPress has been out in the 2.9 version for a few days now, and Donncha has just checked in the 2.9 code into the MU trunk. You can find it here: WordPressMU trunk Scroll down to the bottom of that page and there is a zip link. Do not put this on a production site [...]

