08/31/2009 Update: For Snow Leopard compatibility, see here.
Yesterday Apple release Safari 4.0.3 which, of course, broke MiddleClickClose. Again. The problem lies in the file Info.plist that is part of the plugin. From what I read about SIMBL, good practices said that you should include a key called MaxBundleVersion whose value was the internal version number of the app you were patching. The problem is that every time Safari gets updated, Apple increments that number and SIMBL won’t load the extension any more, since it proclaims that the maximum version of Safari it should be loaded with is the previous version.
I usually play catch-up with Apple and get MiddleClickClose updated a day or two after a new Safari ships. I’ve decided to stop that and have removed the MaxBundleVersion from the Info.plist. This is, after all, a dirty hack, so why not make it even hackier?
If you re-download and re-install, you shouldn’t ever need to update it again. If you already have it installed, you can just edit the Info.plist file that will be in ~/Library/Application Support/SIMBL/Plugins/MiddleClickClose.bundle/Contents, removing the two lines that look like this
Here are the new downloads