I have started using ajax/jQuery in our websites / application. There are many plugins that support degrading the javascript to browsers that dont have javascript enabled an
I know this is a very old thread, but I thought I'd post this for reference:
According to this website, only 0.4% to 2.4% of users had JS turned off. The first test they ran was with about 13,500 users, which is admittedly small for the interwebs, but it's still quite a large amount of people. This data is from 2009