The gadget hounds at Gizmodo stumbled across the file in Torrent, and are reporting to have downloaded and installed it successfully.
The file is apparently called iPhone1,2_3.0_7A341_Restore.ipsw and is listed as 230.1MB.
Of course we'd strongly recommend against going on the search for it, but if you're really desperate to get your hands on it early make sure you synchronise your iPhone before installing so you've got a back up if it does all go wrong.
The author of the Gizmodo article managed to have it all done and working within an hour.
Here at Stuff Towers we're scaredy cats and are going to wait the short seven days to get our hands on the official update. If you decide to go for it, let us know how you get on.