Q:

How much self-control does the Green Hulk have?

In the Avengers movie, the Hulk 

shows a fair amount of self-control by the end of the movie (including some amusing set pieces).

I don't recall this being the case in the comics.  Is my memory/Hulk knowledge faulty, or is this a different angle for the movie?

A:

The Hulk's self-control varies wildly throughout the comics.  At times he's a mindless savage, and at times he has the complete personality and intellect of Bruce Banner.  It was revealed at one point that Banner suffers from multiple personality disorder, and the green Hulk is only one of those manifestations.  The original gray Hulk is a separate personality, which appears to have about average intelligence and self-control.

A:

The movie basically implies that

Banner's 'secret' is that 'he's always angry' (either at himself for his original error in calculation, or just naturally generally pissed off). Either way, it's implied that, certainly by the end of the film, Banner can transform into The Hulk at will. Doesn't explain why he's out of control on the Helicarrier, though - just been suggested to me that, perhaps, this change occurs because he's been prompted by his fall caused by the explosion; I also suggest that the Spear may have had a contributing factor.

