I897UCKE3 - Build date of May 26, 2011
I897UCKF1 - Build date of June 8, 2011
password for both is samfirmware.com
Neither of these have been tested by me so I cannot confirm their stability or quality of build, but hey, official Captivate gingerbread. Means AT&T is going to push out an update to us for real at some point which means more goodies.
So here they are in all their (assumedly) bloaty goodness from AT&T.
EDIT: At least KF1 comes with new bootloaders. If they are anything like I suspect, they are Captivate equivalents of the gingerbread bootloaders for i9000.
EDIT 2: Make sure to use both the included ODIN 1.81 and the new S1JE4.pit file or else there seems to be a possibility of bricking (cannot confirm as I'm unable to test this on my way out the door to work).