The Truth about Cars has been running a series about the history of this sort of behavior. It's mostly about GM's perspective, but it covers the original factors that brought many car companies under one roof and what caused them to become homogeneous and boring.
I was going to get it via my friend Anders, who works at Apple and gets a 15% discount. But it turned out to be faster & cheaper to actually buy it through Amazon, since they're offering a $100 rebate on the $1099 model we want to get, and they don't have charge me California sales tax. On top of that, they're throwing in free Amazon Prime membership, so an upgrade to one-day shipping was only $1.99. Total end cost: $1000.99. Ordered it yesterday, should be here tomorrow.
I'm cancelling the Prime thing after the laptop arrives, though. I just don't buy enough crap from Amazon to justify the yearly cost.