Wouldn't that also depend on the target audience of the site? If a site was targeted at the same people that use HN for example, I doubt they'd have a problem with the site using a .net
Eg. searching for 'python' gets you python.org as 1st result. You don't want to go to the .com
Also, I wonder how many people (say, someone's boss), heard about this cool Python language and just tried python.com. Oops.
Somehow I also remember it's php.ne, not .com, even though I haven't visited that site so much lately.
But both of these were already an established internet brand when I started using them.