At the end of the movie The Incredible Hulk, the one with Edward Norton, General Ross was sitting at a bar, drinking alone, when suddenly Tony Stark appears and they had a little chat. What were they talking about? Has it some relation with some plot of the next movies?
They were talking about the Avengers Initiative, the same thing Nick Fury was talking about at the end of Iron Man. And yes, it ties directly into the first Avengers movie -- it's the reason the Hulk is a member of the group.
If you just watch the scene in the movie, and nothing else, then the conversation they have appears to be about The Hulk. It looks like Tony is about to ask General Ross to help him get Bruce onto the team, or something like that.
However, there is a Marvel One-Shot (a series of short skits set in the MCU) called "The Consultant", which you can find on the Thor DVD release, that tells the rest of the story. The basic idea behind this scene is:
The Security Council that basically "runs" SHIELD wants to get Emil Blonksy (Abomination) onto their newly-formed Avengers Initiative (they consider him a war hero and easier to control than Banner.) Fury has been ordered to send someone to the Army to get custody of Blonsky, but Fury thinks that's a terrible idea. In the skit, Coulson and Sitwell -- two of Fury's top agents at that time -- sit around to try to figure out how to get what they really want, which is Hulk.
They come up with a plan, which is to send Tony Stark in to talk to General Ross.They know that Stark and Ross don't like each other, and that Tony will be able to piss Ross off easily enough. They figure, if General Ross knows Tony wants something, he'll refuse to give it up out of spite, and that's exactly what happens. Ross refuses to consider Tony's request, Fury can't get Abomination, so the Council is basically forced to let him try for the "backup" of Bruce Banner.