What is the standard deviation of block generation times? A block is generated every 10 minutes, on average.
What is the standard deviation of this distribution?

It seems to be a measurable property, not a calculable one.

Is there a chart of the standard dev over time somewhere (should be added to blockchain.info)?
Excluding complications like difficulty changes and temporary blockchain splits, you can model the block generation time as an exponential distribution.

An exponential distribution has a standard deviation equal to the expectancy value. This predicts a 10 minute standard deviation for Bitcoin.



Measuring the actual distribution isn't that easy. While each block contains a timestamp, that timestamp isn't very accurate, and sometimes the time difference between blocks is even negative.
The timestamp doesn't change over the course of a single share, and some miners deliberately use timestamps deviating from the actual time