I ran into an above error,
AWS::S3::Errors::RequestTimeTooSkewed, when I tried to download an object from S3 using aws-sdk of ruby.
[2013-01-29T14:34:35+09:00] FATAL: AWS::S3::Errors::RequestTimeTooSkewed: ruby_block[something.s3.bucket/pub/archive-i-want.tar.ggz] (/foobar/fizbiz/s3.rb line 8) had an error: AWS::S3::Errors::RequestTimeTooSkewed: The difference between the request time and the current time is too large.
It was occurred that the clock of local machine was very late.
I updated the time with ntpdate.
$ sudo /usr/sbin/ntpdate 220.127.116.11 29 Jan 14:28:41 ntpdate: step time server 18.104.22.168 offset -929.483212 sec
If you don't have ntpdate, you can install with yum.
$ sudo yum install -y ntp