Fascinating... I take it that is a screen shot from the SVN? I was playing v26 vanilla and it wasn't there for me. I literally looked right there... which is exactly why I complained about it. The v26 vanilla pedia is in fact a mess. Lots and lots promotions with no explaination of how to get them. If this is now fixed great.
Also, why bother with a BC date at all? (annoying source code demanding it aside.) I personally feel that you shouldn't have a date displayed (turn count or the like is fine) until you research the Calander tech and the concept is actually invented.
Wait Really? I was unaware that the V26 pedia was broken! That's bad, although since we're releasing V27 in a week it shouldn't be too bad.