I don't know how other ppl are finding their build dates (not battery date) but I found out mine by registering my phone with samsung. When I finished typing in my serial number it popped up a manufactured date...theoretically you don't actually have to register your phone to get your date since you could quit the process at that point.
On the main topic, my BUILD date is 7/12/10 and my battery date is 7/1/10. I don't have this screen battery drain problem. I admit I haven't tried the 4 hour test but if I keep my phone in my pocket without looking at it I can go an hour without going down a % (if I'm in good coverage). I can't tell of mine is really blue our just blue (relatively speaking)...but it definitely has a ever-so-slight lean toward bluish. For those ppl wondering wether their phone has the screen problem I think the fact that you aren't sure most likely means that your phone doesn't have the problem. From the sounds of it the battery drain is pretty profound to such an extent that there would be little doubt.
Perhaps it's just defective screens in general with nothing to do with the date of manufacture...it could just be something that always has a chance to happen. I don't see samsung changing their build process that quickly, unless it was something easy to remedy. I guess it's something totally different but this is a company that is taking 2 months and counting to release a software gps fix that, from what I read, sounds like it should be pretty easy make. And if the newer built phones have better gps why isn't there an ota update already? Anyway I guess I'm skeptical that samsungs whole first batch of captivates were flawed. I would think they would have done a recall, especially for something as erroneous as a screen that never actually turns off. And generally skeptical that samsung has changed anything at all in the building of the captivate.