Nanobreweries Defined

I have always felt that a reasonable definition for nanobrewery was any brewery using a three-barrel system or smaller, and now I see I'm correct. John Holl has a nice piece on nanos at, and that's the definition he uses. His source? Me.
Nano-breweries, sometimes referred to as pico breweries, or bucket breweries, distribute to a limited area and only make beer in very small quantities.

How Small are Nano-Breweries?

"My working definition is three barrels or less, which essentially makes them large-scale homebrewers," said Jeff Alworth, author of the Portland-based beer blog Beervana.
Now, if only someone would call to ask my opinion on whether beers fermented with brettanomyces can properly be called sour, we'd be all set.