Could the argument be made that the minority who surf with Javascript disabled don't necessarily have to be catered to, since they will enable Javascript if they trust the site or find it useful?
I think it depends on what content you're providing and which users you want to reach.
I've seen text-only blogs that involve javascript in their visual design and cannot be read without it. I've also seen websites where the site navigation links are rendered by javascript. In both cases the sites are inaccessible to non-javascript users.
In my opinion if you can provide the same content without requiring active scripting, you should. If you're providing an interactive experience that can't be achieved without scripting at least be aware that you're limiting your user base. Even if users have scripting available but disabled by choice, they may decide that your content is not worth enabling scripting for.
I'm also concerned that technical users who disable javascript by choice might not frequent a site like "yahoo" as much as non-technical users. I'm curious if a more neutral but still popular site would have a larger percentage of non-javascript visitors.
That's certainly true for me. I don't care that a site requires scripting, but I do care when there's nothing to indicate that I'd be better off if I allowed javascript.
This is especially true for sites that let a user begin some set of actions (write a lengthy comment, or fill out a multi-step form), and then simply fail at the end because scripting is disabled.
It is trivial to add a "This site requires JavaScript" message. Leaving it out says you either don't give a shit or don't know what you're doing.