Safari is being built based on
Webkit, which is based on Konqueor from linux, but not its being worked on by Apple, Google, Nokia and probably some others.
I'm not entirely sure Safari 2 (is that even the one on Windows, or are you guys on Safari 3) is based on Webkit, it probably is but I can't say for sure. In any case, I have noticed in OS X how much faster Webkit is than anything else I have used. I just don't like how it handles tabs/new windows, but firefox is just as bad. Opera is the only truely great tabbed browser I've used (I'm sure its just what you get used to, but without extensions and configuration Opera will not open a link in a new window unless you specifically tell it to, always a tab). Now I've lost where I was going... but I guess to wrap it up, Safari is making great progress, make things always open in tabs, and make it block ads better (or at least allow a user to manually do that) and I'll be happy.