Is there one? I tried to find one, but after a little searching I gave up and wrote on myself. I use it to manage the favicons on my WordPress MU installs — favicons for each site can be uploaded to one folder and then ‘picked up’ by a little WordPress magic.
If you’re interested in getting it, just post a comment here… if there’s demand, I’ll clean it up and release it. Thanks! 🙂
By Popular Demand, I’ve uploaded the plugin here: http://dropbuzz.com/get-wpmu-favicons/