Well, if I'm not mistaken, WashU's second interview weekend just ended, and they said to expect a decision a week or two after it. So I guess I'm expecting to hear from them this week or the next.
The two interview weekends I am aware of for CMU-Pitt are this Thursday through Saturday, which I will be attending, and Sunday, 3/2 through Tuesday, 3/4. I haven't visited yet, so I haven't had a chance to ask when to expect a decision, but I suspect it will likely be one to two weeks after either the first or second interview dates, depending on how they do things. Although, in my interview invitation, they said, "Indeed, the overwhelming majority of interviewees receive offers of admission, based on experience in past years," so maybe the decision will come more quickly.
Sorry to hear that you didn't get in, but thank you! Along with UCSF, it's one of the two programs I'm most seriously considering.
Edit: I should mention that I applied to the Computational and Molecular Biophysics program at WashU, and it seems like you probably applied to the Computational and Systems Biology program. I was told that, though we all applied to DBBS, each program makes its admission decisions independently, so the information I shared may not be relevant to you.