I thank you both for your responses.
Veilside, I realize I was being a bit ambiguous on my last past. I have, in fact, applied to the Penn Post-bac for next fall. I was just being an anxious applicant and wondering if anyone had some inside information. I have heard the best things about Penn's post-bac, so I haven't applied to any of the others. I know Columbia's admissions is open until June so if I get a big rejection there is hope yet! But who knows, maybe we will be classmates come the fall?
I guess I don't expect this program to "transform me into a stellar applicant" or anything like that. Hopefully, I won't need a complete transformation, just some concentrated work on my language skills before I apply to grad school. Also, I come from a less well-known school and I would assume it would be helpful to establish that I can perform well at a more respected institution, like Penn. And, like you said, Philly sounds like it could be a fun place to live for a year! We'll see I guess. And at least it is a "fraction of the cost" of a regular Ivy leage ed...