Wufoo insists on embedding an iFrame (you can't use your own arbitrary form code to submit to their servers).
I don't think that's accurate. I recall when I was joking with Chris about slamming them with thousands of requests a day, he suggested I look into using locally hosted forms, and just sending the post to them. Since I was joking (and was really only doing maybe a couple of forms per day), I never actually looked into that option. But, I'm definitely having a flashback to that conversation.