Kennedy reacted furiously to the incident during the game and accused Jennings of poking a finger in his eye, although he later claimed to have over-reacted.
At a European Rugby Cup Ltd disciplinary hearing in Dublin today, Jennings was found guilty "of an act contrary to good sportsmanship in that he made contact with the eye or eye area of Nick Kennedy".
The judicial officer Roger Morris from Wales decided the offence was at the low end of the scale and, having taken into account any mitigating and aggravating factors, he banned Jennings until January 6, 2010. Both parties have the right to appeal.
Jennings will miss eight matches for Leinster, starting with Saturday's Heineken Cup trip to Brive and including the back-to-back European encounters with the Scarlets.
He will be available again for their Magners League game against Glasgow at the RDS on the second weekend of January.
The Jennings case is the first high-profile incident since the International Rugby Board vowed to clamp down on the "heinous" offence.
The IRB called for global consistency in how offenders were punished following a spate of notorious incidents, including Schalk Burger's clash with Lions winger Luke Fitzgerald in the second Test.
The Lions felt Burger got off lightly with an eight-week suspension when Munster flanker Alan Quinlan was banned for 12 weeks for a clash with Leinster's Leo Cullen in last season's Heineken Cup semi-final.