Actually, the olympics would probably *lose* prestige on these boards should Federer win gold in singles. Cause let's be franck, what prestige it has was hyped to high heaven by the *************, just because Federer didn't have it (they even chose to "believe" that different olympic golds have different values, which is of course silly). Now, should Federer win and end up with more gold medals than Nadal, the value of the olympics will plumet for the people hyping it on the forum, and it's liable to turn overnight from a "3,000-point event" (ask DRII) to a "meaningless exo ala YEC".
As for "cementing" the place of tennis at the olympics, yeah, it would probably be good if Federer won it (higher visibility, and proof that all-time greats actually care about the event), although the best possible ending to the tournament visibility-wise (ie Federer beating Nadal in the final) is already a no-go, because of (A) Nadal's knees, or (B) the more stringent anti-doping testing at the olpympics (take your, ahem, pick).