I get the feeling the stewards were trying to be consistent actually...they imposed a drive through penalty for Chandok (?) last race, so I think they felt they had to penalise Senna, which was a shame. And although it was a similar incident to Massa, it's hard to compare the two because they are different series even if they are roughly the same. I don't think they should have penalised him though 
Does anyone know what happened to the driver that had the massive smash mid-way through the race?
And is it just me or is GP2 a lot more interesting than F1 at the moment 
The main difference between Chandok's pit incident and Massa's/Senna's is the that Chandok got infront of the car he almost hit, which did seem to be a bit reckless. There was controversy 2 weeks ago about the similarity between the incidents, and the difference between the decisions. And today's incident just highlights that further because it was EVEN MORE like Massa's incident that went unpenalized.
I slightly a agree with you that GP2 is more interesting than F1, but not just "at the moment", its been for the the last 3 years at least. F1 has been improving, but i would like to see more improvement, in all areas, but in particular even handedness of all teams.