i dont think any of the genin know about it. its not like anyone has said outloud that naruto has kyubi in front of ANY of the genin. hell many jounin didnt even know he had the kyubi, when he is fighting neji the two jounin beside hinata are shocked at naruto's power, and so is the referee.

i dont think its supercommon knowledge that naruto has the kyubi. i think that many of the adults do but it seems there is a cutoff somewhere(since many dont). i would guess only those that were at the battle against the kyubi know, and even now are following the 3rd's wish to keep it a relative secret. just because he is dead, he was loved so greatly that i doubt they would start chatting about it openly, probably as one of many laws he set down that they are keeping out of respect or simple common sense since it shouldnt be common knowledge.

even when fighting itachi, i dont think sasuke was paying attention enough to find out WHY they were after naruto, he just knows his brother is after him. he has seen naruto show this tremendous power but how the hell is he or anyone else supposed to just guess that the kyubi, a uberdemon that was 'defeated' years ago, was actually sealed in naruto? we know it cause we read but the characters sure as hell dont know any of that.