[jessor]

NoScript has 74,459,688 downloads so far (https://addons.mozilla.org/en-US/firefox/addon/722/). You'd have to do some calculations with this to get closer to a real user number, though ;)

I'd wager that the average NoScript user has at least two machines, so the total number of NoScript users is probably less than 2.7 million. (http://blog.brandonbloom.name/2010/06/noscript-add-on-instal...)

[lukifer]

I'm also guessing the majority of NoScript users have exceptions whitelisted for many trusted sites, given how many sites are completely useless without JS.

[Xurinos]

Yes, and I happen to have Yahoo! sites on my whitelist, which tells me that their stat is not reliable. The actual percent of users who block JavaScript may be higher, given selective blocking, as provided by Opera and Firefox's NoScript.