With my DS when he is intensely doing something and someone interfers with his goal he can get aggressive. Sometimes he is so driven he forgets about what is important. The situation has improved over the years. It's hard to help him becuase it is natural to be mad and that makes it worse.
My ds, now 9, was a pretty aggressive guy as a toddler, and for several years after. For instance, if he wanted to give you a hug, he would run at you, full throttle, practically knock you over or bang into you hard to deliver the 'hug'. It was disconcerting. Also, in play, he is very hands-on wants to hug people, preferring more physical contact than most kids it seems. As for behavior when frustrated, if we needed to interrupt an activity, etc., he would kick and scream more often than not. I remember we were at a restaurant around age 1 and he was upset about something, started thrashing around and ended up banging his face straight down onto the table, well that huge bruise looked great for several days!!
Also extremely high energy, creative and seemed musically inclined/interested in rhythm, I figured I would put him in tap class and maybe that would help get some exercise/some of that aggression out, and perhaps instill some sense of grace.
Probably most of his progress is just in growning out of this phase, greater ability to express himself, etc., but I think the dancing was and continues to be a great activity for him. A place to enjoy his body rather than get frustrated with it, and a time for relaxing/fun music and as he put it to me once, it is nice because he is able to stop thinking quite so much. In short, I guess it is relaxing for him.
We are living through this even more intensely with dd3.5, though perhaps my memories of ds are softened. She is amazingly aggressive, frustrates extremely easily, although often reasonable discussion will calm her. I am focusing on trying to get her first reactions to be 'oh I need help', instead of 'AAAARG!!!'. It is taking some time
