I thought I heard someone say something about Sarah Chalke being it... but I might be totally spacing out.

They haven't revealed her yet, some people were saying there is a rumour that Sarah Chalke is the mother but I doubt that will be true. It probably won't be revealed until the end of the whole series.

Its meeeeee...
sorry...no they havent..i doubt it would be this subtle since its the big mystery on the show..and they kinda keep people hooked by throwing in clues..wrong ones and right ones.

Guys, guys. The mother is Barney. How's that for a shocking twist?!?

i think we got a glimpse of her in the st patricks day episode, ted mentions she was there and theres a part where he bumps into someone and says sorry, it seemed like it would be pointless to show if she wasnt part of it. Maybe im just paranoid though :)

They haven't yet, but if they don't soon then they come rely screwed it up, because 2030 is only 17 years away and the kids we older than 17 so that wouldn't make any sense.