I too have been trying to track down the song that is playing when Samantha approaches Jake at the coat check. I listened to the song "Take a Chance" on iTunes as previously posted and I found that the lyrics match the song that is playing in the movie, but it is not the same singer. Maybe Divinyls is not the original singer/writer of the song?
Also I've found some confusing things on the web regarding the song "Ring Me Up" and "Take a Chance." When I look up the lyrics for "Take a Chance," they are completely different lyrics than the lyrics I hear when I play the sample on iTunes and Yahoo Music. The same goes for the lyrics of "Ring Me Up." The lyrics I found for that song match the song that is featured in the movie, but when you listen to music samples found on iTunes and Yahoo Music, it's a totally different song. That is why there is some confusion regarding the Divinyls song credit for the movie.
Anyways, I just watched the movie and was listening carefully to the song as it plays during the scene and I distinctly heard (after all the oo's and aah's), "Yooooouu are my desire," then something I couldn't understand and then, "Know you're out there, know you've got a heart..." But again as I said before, these lyrics match the Divinyls "Ring Me Up" song, but the singers don't match.
I wish we could find out if they originally wrote the song or maybe someone covered the song????