I'm working on version 0.51 that at least will support redirects. Meaning it will also pick up icons behind tiny-urls etc... though im having some problems getting it implemented for all cases.
You can see the latest code in the Trunk though further development on the redirects has to be done.
Current version 0.50 has one none blocking bug: in the table wpfavicon-2 you see that the return code (200,404 etc...) is not logged. Whatever. Will also be fixed in the next version.