The probability of encountering a $ sign somewhere inside URL is not insignificant... I agree that it's very unlikely (perhaps even illegal) to use ^ in URLs, but $ are sometimes used.
I'd have to take a look at the spec, but I think both characters should be URL-encoded anyway. Maybe it'd be a good idea to include a URL-normalizing filter that would encode everything properly (according to www-url-encoding) before regexping?
D.
