Well, next time you get to the Turret redemption line, look for it. It's on the second line (there are two, so it won't appear on the first one) You could also just start The Escape chapter and you should see it. IT TALKS ABOUT THE LEMONS!! It also specifically says "Her name is Caroline." And it's most likely talking about GLaDOS.
Also, if you're like me and are completely insane, what do you think the chances of a Portal/Half Life Cross-over are? I think that is the very reason they've been pushing off Half Life 3. IT WOULD MAKE COMPLETE AND TOTAL SENSE!! I'm thinking of either writing a RP or a Fanfic about it.