Gingerbread (the Android 2.3.2 version) has been leaked for the Samsung Galaxy S i9000. Users at XDA Developers are saying that it includes Touchwiz 4, and download mode is still available. It also looks like Samsung is now using the ext4 file system, which should bring performance boosts much like the ones on the Nexus S.
Remember, this is a beta build -- at best. I wouldn't recommend anyone run and flash it, but in the hands of developers it's like 24 karat gold -- possibly leading to things like CyanogenMod 7 for Samsung Galaxy S phones. What this means for US customers who are tied to a carrier for upgrades is unknown, but at least Samsung has Gingerbread in the works. Check the source link for download locations. [XDA-Developers] Thanks everyone who sent this in!
Update: Supercurio, of Voodoo fame, has had a look and verifies that this does not enable the ext4 file system. His word is good as gold when it comes to the Galaxy S -- blame excited users and bloggers for the mix-up.