I have listened very carefully to this prank call (below).
I am convinced that it is the pranksters themselves who were pranked. It is obviously not Sarah Palin on the line. The voice is far too girlish - there's too many little giggles and "aw shucks" remarks. In particular the "We love you" is far too over the top.
I am convinced that it is Tina Fey impersonating Sarah Palin on the recording. The "maybe in eight years" remark is just like Tina Fey.
And obviously, the real Sarah Palin would have smelt a rat with the "Sarkozy" reference to hunting by helicoper, rather than saying: "We should go hunting together". And obviously Sarah Palin would have realised that "Sarkozy's" reference to "my Special American adviser Janny 'Alliday" indicated a phoney.