[star0zero]

I've heard this figured bandied about quite often, as well, and I think it's mostly anecdotal and should be taken as a general rule rather than empirical fact.

[Vomzor]

This is a very old article. 10.000 hours originates from this article. It's the original.

[vwinsyee]

I believe Malcolm Gladwell was the guy who came up with the "10,000 hour rule". [1] Norvig's article actually quotes Gladwell as the source of the 'rule'.

[1] http://en.wikipedia.org/wiki/Outliers_(book)