like above people said, the chances are very high, but it depends on the program. if they flew you out, wined and dined you, that means you are their top candidate and have strong chances of getting in. i mean, they wouldn't spend their resources on you if they didn't want you on the first place. they like you, and that's why they invited you... so that both you and them could get a feel of each other on a personal level. i got a phone call this afternoon from the PoI i want to work with, and i interviewed at this university a couple weeks ago (they paid everything). i was freaking out as well, because i was the one with the lower hand. but things turned out well.
so, hang in. you should be getting the good news through phone or email in a few days.