I don't post too often on these threads, but I thought I would let you guys know what happened to me (because this past week, I was also very curious as to if other people were being contacted).
So, it sounds like I received an email similar to the one aquila456 received from Ms. Sheffler. I got mine late yesterday afternoon. I was invited to and attended Penn Preview, so my email was more like her saying "I said I would follow up, so I wanted to make sure we touch base. Give me a call." I phoned Ms. Sheffler this morning, and after discussing my current situation (the school I was currently enrolled, the school I recently got off the waitlist, the weight of finances in my decision, etc.), she basically told me she'd round up a financial aid package for me later today, so I could better assess my decision to go to Penn. I think she also said she would call me, but I was so darn nervous, I don't exactly remember what I/she/he/they said.
I guess it technically wasn't an "acceptance" (and to be quite honest, at points it seemed she was simply following up because she promised she would, since I had attended Preview), but I've also heard schools of doing a very similar thing-- not officially accepting a student until they're quite sure they want to be there. I've heard this plays with their numbers a little bit (skewing their numbers to seem as if they accept a fewer number of students), but I guess this is all hearsay.
Anyways, needless to say, I'm THRILLED. Penn was my top choice for forever. Now, I'm just waiting for the official green light, and I'm almost positively there! But yeah, let me know if you guys have any questions about what happened, etc. This is going to be a tough couple weeks for us all, so haaaaaang in there!