If Vettel and Webber were in different teams, it would be a very silly incident. Given that they are in the same team, it's even worse, and a reflection on the intense rivalry rumbling underneath.
There is a clear distinction between "Vettel turned to the right", and "Vettel turned suddenly to the right". In this case, Vettel did not turn sharply to the right (it looks like that from the track-cam, but look at the onboards). Actually Webber pulled to the right on the straight, and then he moved a bit to the left to provide as much squeeze as possible to Vettel. If they are opposing teams, this is called "racing". If they are team-mates, it's called "madness".
The reason Vettel turned to the right was probably because he was thinking of the better braking grip slightly to the right. In that situation, normally the other car (Webber) would just co-operate and move to the right, especially since that the corner was lost really. Webber decided he was going to put up a fight, and just held his ground. So I would classify it as a racing incident. However from a teams point of view, Webber should have not squeezed Vettel as much, and should have obeyed Vettel's movement approaching the braking zone.
As Christian Horner said; "The large mistake was that not enough room was given".
I don't want to talk down Webber; he's a great driver. I don't care who the other driver is, I'm just giving a common sense point of view, in particular from team perspective.