I already had two EVs I liked (a Roadster and a RAV4-EV) before the Model S came along. I'd also taken several L2 road trips, which were nice except for the charge rate. My interest in the Model S was almost entirely because of the promise of fast charging - as others have noticed, they had long promised a 45-minute quick charge, but had never given any details of how, when or where that would happen.
Sig buyers had to lock in their orders by the end of July 2012. There were repeated rumors from the stores that there would be some announcement on fast charging during the spring and then the summer, and as GG notes some had seen a mysterious fast charger at the factory. At the first test drive event in Fremont (June 2012) I asked George Blankenship about it, and he said that such announcement would not come until after Sig buyers had to lock in orders.
I made a complaint or two on these forums, and nearly canceled my order as fast charging was critical to me. But I talked to somebody I knew at corporate. Of course this person could not give me any details, but I explained why I was buying the car and that I did not have enough information, and wondered if I would be disappointed with the car. I was assured that I would be happy with it. Still shy on details, but trusting Tesla to deliver something useful (just a CHAdeMO adapter would have been nearly good enough for me given all the stations in WA and OR; at the time I assumed that would come faster than Superchargers in WA, silly me. They didn't promise one was coming, but did say that enabling charging anywhere possible was a goal of theirs), I locked in my order on the last day for Sigs, July 31 2012.
The fact that the Superchargers were free to use was a surprise.