The Netcraft toolbar is also available for Firefox.
"it's probable that most Firefox users aren't going to download Google's plug-in because they aren't aware of the threat of phishing"
Neither are IE's users, of which there are far more. Why is this even relevant to the idea of integrated anti-phishing? Firefox has had anti-phishing features in one form or another before IE7. And regardless of who had it first, both browsers are incorporating anti-phishing technology, and that is to be praised, not bashed because you don't like one browser or the other.
Get a life. It's software.