Can you explain what exactly happened?
Between the 1st and 2nd rounds, St-Pierre's cornerman, Phil Nurse, rubbed Vaseline on his face then his body. Between the 2nd and 3rd rounds, he did it again and the State Athletic officials freaked out. Between the 3rd and 4th rounds he did it again. Guards then made a horrible attempt to towel St-Pierre off as he stood up.
What's the big deal about some Vaseline being on St-Pierre's shoulders, back, and chest?
It makes it easier to fend off submission attempts and work through your opponent's guard. You could see Penn trying to raise his legs up onto St-Pierre's back multiple times (2nd round especially), but they'd get to St-Pierre's shoulders then slide down to his lower back. St-Pierre isn't posturing up when this happens, so it's not a matter of his movement disrupting things.
The 1st Round was basically even. The 2nd Round doesn't get bad for Penn until about the 3 minute mark. Following Penn's attempts to position his legs high on St-Pierre's back, he loses his guard and gives up side control. Joe Rogan makes a big deal about this because it's extremely rare for anyone to get through Penn's guard. Perhaps Penn's legs were a little slippery following the multiple encounters with St-Pierre's back and shoulders a minute earlier. After this point, Penn begins to take strikes. The fight is never the same. Penn looks out of it in the corner from the strikes and the amount of energy he used to defend from the bottom.
Will the Nevada State Athletic Commission do anything about this?
If the fight was overturned and ruled a No Contest, I'd be shocked. My guess is they will at least fine and suspend St-Pierre's cornerman. It would not be out of the question for him to be banned. This is a serious matter. It happened in one of the biggest fights in years, on Super Bowl weekend, and in Vegas. There are a lot of people who lost money on this fight wondering if the State Athletic Commission did their job correctly.
St-Pierre himself will escape without any official reprimands, although this makes his win a little less sweet.