This is not unlike the people who had to wait for the Toyota Prius. In the case of the Prius, demand exceeded supply, so people had to wait. As I recall, some dealers did ask for a small deposit to get on a list for a Prius.
There are 2 different approaches to deciding to get the Smart Car: (1) Wait until users get their car, drive it for a while, and depending on what they say about it, decide then. In this case, you may have to wait until around January 2008 to around March 2008, to see. (2) Put a deposit down now, and at a later time, decide to go for it OR ask for your deposit back.
Right now, there appears to be a 1 year waiting period due to the high demand. While it's hard to say what will happen in the future, I believe that once the cars start appearing in sizable numbers on the US Roads, demand will increase. In a way, the users become an unpaid sales force every time they show off their car. After going to the LA Auto Show, I have seen that this car grabs everyone's attention.
Bob Diaz