Of course Firefox 1.5 works. So does Camino, the Cocoa Gecko browser. Camino doesn't have all the FF extensions I use (no Google toolbar, no Google bookmark synchronization, etc), but it does have features of its own:
Camino incorporates features that use Spotlight, Address Book, the Keychain, the Finder, the Dock, Bonjour, Services, and System Preferences.I'll try alternating FF and Camino for a while and see which I like better.
Update 9/24/06: Camino is impressive. It's much faster than Firefox on my old G3 iBook, it works with all FF sites, and I don't have to deal with Adobe's kludged PDF integration -- Camino just downloads the PDFs. I like the fine touches, like the "Search this site" option in the embedded Google searchbar. I love the Keychain integration -- that makes up for all the missing Firefox extensions I can't use. It's my browser for now.
Update 9/24/06: Still enamored with Camino. It uses Gecko 1.8, same as FF 1.5. (FF 2.0, due to ship RC1 on 9/26 uses Gecko 1.9.)