Yesterday night, a build of Froyo for Galaxy S was leaked by a previously relatively unknown Samsung firmware site Samsung-Firmware.com. Now, keep in mind, while this is an official build that came from Samsung itself, it is only a test version still using an Éclair kernel.
I wouldn't recommend you flash it just yet - instead we can enjoy this 9 minute video preview by the guys from HDBlog.it who already dared to take this ROM out for a spin. HDBlog.it is an Italian tech blog, but they were kind enough to provide an English version (though the speaker has a pretty heavy accent).
According to the tester, this test version is perfectly usable, although the original leak mentioned it was still a bit too slow.
Without further ado: