UPDATE: this method should no longer be necessary. See the Comments below for the latest.
If like me, you’re not impressed with Dropbox drawing huge green blobs all over your Finder windows without even asking, here’s a great tip from Zackary Corbett for getting rid of them. Run the following line in Terminal:
pluginkit -e use -i com.getdropbox.dropbox.garcon
Thanks Zachary 🙂