OK you X and O types, what can you tell me about the Iso running play in football?  I'm a person that's learned everything he knows about football from the Madden video games.  This Iso play is new to me in the Madden '10 playbooks since my last version ('08).  I only remember inside running plays called HB Dive, HB Inside, HB Gut, HB Slash.  But now I don't see the Dive anymore, I see the Iso.  I also heard a TV commentator mention "this is just a simple Iso play" and I somewhat recognized the replay from Madden.

So what are the mechanics of this play?  I only see it in formations that include a fullback (I-form and offset I).  So is there a preferred gap that the Iso is designed to exploit?

I know that there are lots of Madden players on these boards, and there are lots of former players of the non-joystick variety of football (you know, that kind that they actually play on a real field, with a ball and everything), so hopefully this isn't too off-topic and will be interesting to somebody other than just me.

I have all sorts of other football (well, Madden) related questions that I might post every once in a while if X and O talk is encouraged. 

Just a curiosity from somebody who has never played the game but loves to watch it:

What advantage or disadvantage do offensive and defensive linemen get from their pre-snap stance when they have 1 hand on the ground or both hands off the ground (or do they ever have both hands on the ground)?

I read an article today mentioning moving Hali from DE to OLB in the 3-4 (not sure if this applies to the 4-3 under, but that's another discussion).  The article said that he would move back and have both hands off the ground instead of 1 hand on the ground before the snap.

And on the offensive side of the ball, I notice that a lot of the time the tackles and guards have 1 hand off the ground. 

What does this contribute to the technique of playing on the line?