I know, I know, I'm totally obsessed, LOL!
I think it may come out that part of why Ted is so upset is because he thinks that Barney threw away their friendship just to nail another chick. I think that's part of the problem, I don't think anyone realizes that Barney wouldn't have slept with any other of Ted's exes no matter the situation. But it was ROBIN! I don't think anyone gets that Barney does have a thing for Robin and has held back on any of those feelings, even acknowledging them, because of his friendship with Ted.
I think there was a point to the fact that Ted asked Barney what happened exactly. And that was BEFORE Ted wrote him off, it was as if Ted was giving him a chance to explain it some way that made sense, and instead Barney made the comment about "positions?" which likely just added to Ted's feelings of disgust that Barney didn't value him, their friendship or Robin all that much if she was just another notch on his belt. I think, hope that the truth will come out thanks to that bit in their conversation. It opened the door essentially.
And I could so see a scene where Ted basically calls Barney on this, and Barney is shocked! Basically saying that he thought Ted was THAT mad at him because Ted realized that all of the time Barney spent trying to convince him to not move in with Robin, not keep things going with Robin, etc. was because deep down, Barney had feelings for her himself all along and was being selfish. And THAT Barney could understand being a reason for why Ted so turned against him, but for Ted to think that for Barney it was just about nailing another girl? It shows how little Ted really does know him. And then THAT would explain the spoiler about Barney's "hatred" of Ted. I mean, really, cuz I can't see where the hatred could possibly come from at this point.
Also, I was actually thinking on the fact last night that every season has ended with a break-up: S1, Lily/Marshall, S2, Ted/Robin, and now S3 will probably be Ted/Barney. And like in seasons past, we'll come back from the break and part of the first push of the season will be getting that relationship back on some sort of track.
And we can get some Barney/Robin tension, etc. building. Esecially if everyone (but Robin) knows that Barney actually has legitimate feelings for her, and has for a while.