Quote from: kjj on September 22, 2011, 01:58:48 PM

With regards to the suggestions of integrating NTP into the bitcoin client, I think it is a bad idea. The bitcoin client is simply not an appropriate place to put timekeeping software.

If I were emperor, I would make the client turn red if it thinks the local clock is off by more than 5 seconds from what the peers report, and refuse to run if off by more than 30 seconds.

Code:

Added time data, samples 405, offset +0 (+0 minutes)
-86493 -86018 -3606 -277 -168 -121 -100 -98 -87 -80 -79 -75 -74 -60 -56 -54 -53 -52 -36 -36 -36 -32 -31 -31 -30 -29 -27 -26 -26 -26 -24 -24 -23 -22 -19 -18 -18 -16 -16 -16 -15 -14 -14 -14 -14 -13 -13 -13 -12 -12 -11 -11 -11 -11 -11 -11 -10 -10 -10 -10 -9 -9 -9 -8 -8 -8 -8 -8 -8 -7 -7 -7 -7 -6 -6 -6 -6 -6 -6 -6 -6 -6 -6 -6 -6 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -4 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -3 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +0 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +1 +2 +2 +2 +2 +2 +2 +2 +2 +2 +2 +2 +3 +3 +3 +3 +3 +3 +3 +3 +3 +4 +4 +4 +4 +4 +4 +4 +4 +4 +4 +5 +5 +5 +5 +5 +5 +5 +6 +6 +6 +7 +7 +7 +7 +7 +8 +8 +8 +9 +9 +9 +9 +9 +11 +11 +13 +14 +14 +15 +19 +20 +20 +22 +23 +26 +26 +37 +43 +44 +45 +50 +59 +85 +87 +93 +96 +124 +126 +169 +189 +284 +311 +3596 +3687 +7217 +83428 +5654326511063269263 +5790349588594885090

Some of these systems need a color worse than red, but I think 5 seconds is too tight. 1 minute would throw a blanket of most of them, and a popup message to the rest pointing them to instruction on how to fix their clock would suffice for the rest.
It's interesting to note three are 1 hour, one is 2 hours, and three are ~24 hours off. I wonder if that is deliberate (run your computer in a different timezone so you now when to skype your grandkids), or a curious mistake.