You'd think it would be easy to find Firefox 1.5 just after its release, but at the moment getfirefox.com is forwarding to mozilla.com, which links back to getfirefox.com... mozilla.org has a big banner telling you to go to mozilla.com; but it does link to "Firefox 1.5 released" in their news area. That takes you to a page with the release candidate, but if you click "Firefox 1.0" it will take you through to the Firefox 1.5 release page.
Mozilla's flagship product has a major new release, yet their web presence is a mess. Whoops!
So anyway, if you still care about Firefox 1.5 after all that, head over to www.mozilla.com/firefox and grab a copy :)
All jokes aside, I'm not seeing much on the Firefox 1.5 release notes which explains why this wasn't just a point release to 1.1. Yes, I know it's just marketing hype and not a real version number; but it still irks me when people treat ".5" like a major version. The only notable feature addition is the automated update, which should definitely make life easier. The rest... well the rest isn't going to impress Opera users, who've been enjoying features like 'clear private data' and drag-and-drop tab reording for a long time now. Good to see them added to Firefox though.