I think this was done to create some conflict that will eventually lead to Leonard/Penny again. I don't think honestly Raj would go after Penny because I don't think he would do that to Leonard, and I believe he will be the one telling Leonard that Penny told him that she shouldn't have lost him, and that might be the clincher that ends what I assume would be quite a quarrel between L & P come the beginning of Season 5.

I think it was put in to give Leonard and Penny another obstacle - Priya's gone, so it should be okay, let's get back together, especially after Penny's confession in the finale. So I think it'll always be lingering there as another thing for them to overcome, but I don't think it'll be talked about that much after the first couple S5 episodes.

^ I was pretty much going to say exactly what you said, supermurph.

I kind of think it will cause more problems between Leonard and Raj to be honest. It's more of a betrayl as a friend to sleep with your ex then it is the other way around. But I agree I don't see Raj pursuing Penny at all. Granted there's gonna be some Penny & Leonard conflict no doubt, but I feel like it will be more awkwardness between each other then fighting just yet. That will come later I bet in the source of one big fight maybe?

My personal guess is that Penny & Leonard wind up either hooking up or getting back together at Howard's wedding when ever that happens. Something always happens between people at weddings.

This or the game-changer..

^^ yeah, I think it will on the outside (as in shown) affect Raj/Leonard, but it'll be like the elephant in the room for Penny/Leonard.

but if the bbt writers totally drop it i wouldnt be shocked... theres a bit of lack of continuity sometimes :P

I don't think they can totally drop it. I'm guessing it'll serve as a test for certian friendships, and it'll be the thing that keeps Leonard and Penny apart for longer, since they're obviously in similar places now.

Just based on how they've just dropped stuff in the past, Stephanie, the end of S3, and everything. I mean, yeah, it could be mentioned in the future, but seeing on the past, I'm guessing it could just be forgotten.

Yeah...it's possible...I think it will be mentioned some, though.

I think it will cause problems between Raj & Leonard at first and after a heated argument Raj will tell him it was a drunken mistake and tell Leonard what Penny said in the final about it being a mistake breaking up with him. I think it will cause a strain on Leonard and Pennys friendship at first but i think it will help them come back together (as i think it will force Penny to confess how she really feels about Leonard) at least i hope : )