I just tried Firefox 1.5 on the Powerbook and unfortunately I’ve had to go back to 1.0.7. My whole reason for upgrading, other than it is the latest and greatest, was that 1.5 was supposed to fix the Java issues (basically won’t run applets) Firefox had on OS X. That problem did go away and my applets seem to run fine. However another more serious problem arose. It seems once you run an applet, the trackpad two-finger scrolling stops working (just in Firefox). If I restart Firefox, everything is fine until I run another applet and then the trackpad stops working again. Anyway, like I said, I’ve gone back to 1.0.7 and I’ll look into whether this is a known issue or not. Hopefully it will be fixed in future versions.
Update: Seems this is a known issue.
Another Update:: The Bookmark Synchronizer extension also doesn’t work in 1.5, so I’m definately going to stick with 1.0.7 for awhile.