EDIT (7:06 PM Central): Another abort, this time at ignition. They actually ignited the rocket, and immediately aborted the launch. At this time, they are attempting to figure out what went wrong, and I suspect we'll know something by tomorrow or the next day.
EDIT: Launch time is now 5:05 PM Pacific time (which is 7:05 PM here in the Midwest).
EDIT: Elon Musk posted this update this morning:
The abort that occurred a few minutes before T-0 was triggered by our ground control software. It commanded a switchover of range telemetry from landline to radio, which took place correctly, however, because of the hardware involved, this transition takes a few hundred milliseconds. Before it had time to complete, our system verification software examined state and aborted.
Our simulations done beforehand all passed, because the simulator did not account for a hardware driven delay in the transition. We considered putting the vehicle into a safe state yesterday and updating the ground control software to make the very minor fix needed, but the safer course of action was to stand down.
Yesterday afternoon and evening (Kwaj time), our launch team updated the software to address the timing issue and verified that there were no similar problems elsewhere. We ran the software through several simulated countdowns and then once again with the rocket and range in the loop.
All systems are now go for launch with T-0 at 4pm California time today (Tues).
So yesterday SpaceX scrubbed their attempted launch of their Falcon 1 rocket. Reportedly, the scrub was due to a range telemetry problem.
No word on a reschedule yet, but when it happens I'll let you know.