It’s fairly limited: taking over maintenance for popmail or forking NTPSec certainly isn’t nothing but his reputation is built on the Cathedral and Bazaar essay getting attention at the right time in the 90s when open source was really taking off and his subsequent OSI work. I’d wager that an order of magnitude more people heard about fetchmail from his writing rather than the other way around.
That’s not to say that his open source projects aren’t useful, only that there are thousands of other developers who’ve done work of similar scale and adoption.
