OP, I am having the exact same problem. Went to start the car one morning and it would just turn over and over but would not start. After a few attempts, it would start. Later, it would just turn over and over again and not start. I got it to start once and it ran for about 20 seconds then dies. Then it would just turn over and over again but would not start.

One thing I do notice, is that normally, as you turn the key to on before starting the car, you would hear a sound (I assume a fuel pump) sound. But in the times it would not start, I do not hear this sound. Everytime I try to start, if I hear the pump sound before starting, then the car would start, otherwise it will n ot start and the engine just turns over and over again.

Its a 2007 limited roadster and only has 25k miles on it.

Does this sound like the RCM board issue that is discussed here?