It possibly could be electrical; meaning, that the distributor, is not allowing "ignition" or spark, in order for the engine to start. Just had this happen on my 1994 Honda Civic LX; all of a sudden, my engine, just cut-out, and quit running, while I was moving in the stream, of traffic. Threw it into "neutral" and coasted into a right-turn, and into a parking space. I didn't have any symptoms (of not starting--and waiting a period of time, and restarting. Also, had diagnostics performed, in order, to confirm, that my distributor, failed. This just happened, yesterday, 11-08-10, about 2:20-2:30 pm, Arizona time. Hope, this helps!
PS--It could also be your fuel filter, if it hasn't been changed, in 15 to 30,000 miles; symptoms, are usually, hesitating upon accelerating, or bogging down until speed builds-up, and you have a constant feed of fuel pressure.