It seems to me that Amazon likes to do things really thoroughly. They start out by specialising in one thing (selling books) and use the infrastructure to diversify (selling consumer products) and the expertise gained to make new products (AWS). I'm really excited about this, if only to see outspoken Jobs, who rubbishes competition quite easily, pitched against old school Bezos, who refuses to even talk about the competition.
I get the impression that most product teams at Amazon contain about 5 people.
I love Amazon, btw, I just think they keep the teams lean and do amazing things.
"If a project team can eat more than two pizzas, it's too large." -- Werner Vogels Amazon CTO
If I remember correctly from a visit out there a couple of months ago, they top out at around 12 people on a team (as the other reply mentioned, they're internally referred to as "2-pizza" teams).
So, why didn't they do nothing for two years?
One week before Apple supposedly will announce the iTablet, Amazon creates a press release saying a limited beta of the Kindle SDK will start next month!
If you are the market leader, why would you wait two years for yours competitors? Doesn't make sense to me.