It seems that both satoshi and the first early adopter (who picked up block 12) have stopped mining shortly after Jan/09/2009 04:33:09 [3PM EST]. Bitcoin was essentially dead for 24 hours, until satoshi put his rig back on (and in doing so, reset his extraNonce and begin the next iteration) and found block 15 on Jan/10/09 04:45:46 [3PM EST]. (He then found block 16, an impressive 12 seconds later (a record at the time.))
I'm not certain why satoshi mined block 0 on the 3rd, and then waited for the 9th to release the client. There's probably a good reason, but we'll see. Maybe.
...Edit 16:14. From the data I've got so far, January 10 is cut in half. Bitcoin "died" again at around 7 AM [6AM EST], to be revived at 3:30 PM [2PM EST], 8 hours later.
Odd timings. Why would Satoshi drop out at 3PM and not restart for an entire day, then next drop out at 6AM and revive at 2PM? If 3PM was in his local time at night and something caused his computer to stop (a bug, perhaps, or network problem; has happened to me many times with overnight runs of something), then what caused a stop halfway around the clock at 7AM, which would likely be during the day?