I thought the move was hilarious because it looked so familiar, but obviously looking in detail it was very different.
When Rossi passed Stoner in 08 he was on the inside, braked deep and that put Stoner in a position where he HAS to concede the position. The main danger of Rossi's 08 move was his re-entry to the circuit because he was sliding onto Stoners line with little control. I think this has already been pointed out by someone else.
This year Marquez decided to pass on the outside, which means if he can't get almost all the way past Rossi on the brakes (unrealistic), Vale ultimately has control of when Marquez can turn into the corner. Rossi was always going to let off the brakes and go as wide as he can to defend. By doing what he dad Marquez assumes pretty much all of the risk of the move himself, so the danger/safety side of the pass is much less incriminating for him than it was for Rossi.
A question i found myself asking and I will ask to you guys on here is: Had that pass happened at a more conventional corner, for example turn 1 & 2 at Misano or Catalunya, do you really think Marquez would have gotten away with it?? Personally I don't.
I think the benefit of the doubt could be argued on both riders parts on the basis of intent. Does anyone think either of them ever wanted to go off the road there?? I don't, but if it had been a little trip accross a flat tarmac run-off area I would be much more sceptical because it could easily look like 'the easy option' or taking the piss entry speed wise because you know you can.
The move was clearly seen as a racing incident, and I am thankful for that because what I would hate to see in motogp is a situation where it gets like F1. When the sports goes publicly into the field of altering race results by debating technicalities of who was how far past at what point, everyone loses. For as long as incidents like this remain relatively few and far between they can continue to be taken at face value, so hopefully the riders don't get too carried away and force race direction to step in more often.
The thing that really annoys about this culture in F1 is situations just like the one we saw this weekend where a faster rider is forced to brake on the outside by a defending rider, who then brakes deep knowing he'll run to the very edge of the track because by doing so the attacking rider is forced off the road and into a penalty. It's ugly. So I say good on Motogp for letting these moves go as much as possible.
On a final note, Marquez was clearly substantially faster than Rossi yesterday, he would surely have got past shortly after if not on that attempt, so very much unlike 2008 the move this year was not decisive or particularly consequential.