For one, I disagree with the people out there who insist that everything should function without Javascript. It is nice to code to the lowest common denominator in a lot of cases (for example, I would be really pissed if my bank's site required Flash or some such nonsense.) But realistically almost everyone has Javascript enabled these days and if used properly the resulting sites can be quite spectacular and useful! (I mean, let's see how nice Google Maps is when Javascript is turned off...)

However, this should not absolve you from at the very least ensuring that your page fails gracefully if Javascript is not present. Never EVER leave your users staring at a half loaded, broken page with no indication as to what went wrong. Just ask yourself: Would I rather spend 2 minutes coding up a "This page requires Javascript" message or receive 10 emails daily from users telling me that my page is broken because they have noscript enabled?