Apple is not that important. Seriously. They make very pretty products. But they aren't shaping the developer landscape, outside of a few segments of the industry. I went to YAPC::NA a week ago...350-ish people, 10-15% Mac users. I went to a Sun-sponsored, Open Source focused event a few months back...~1200 people, 15% Mac users, tops. Even at Startup School (where folks like to talk a lot about "wow, look at all the Macs!"), 800-1000 people, 30-40% Mac users.
It's really easy to look around at all of your friends and say, "Wow, everybody is using this, and thinks it's awesome! It's really going to take over the world!" But, your friends are not a representative sample of the development world.
So, Objective-J is a cool idea, and if it helps 280North (who are smart, nice, cool guys doing great work) get their product out the door faster, I'm excited about it. But, I've also looked at Objective-C and Apple's development environment, and came away far less than impressed. While it may be superior to working in C++ (or plain ol' C), it's probably not even better than Java for getting things done (and that's not all that good), unless your problem set happens to overlap very closely to what it was designed for.
There are already several revolutionary JavaScript libraries and toolkits out there (jQuery, YUI, ExtJS, Dojo, Mochi, etc.), and they're all making an impact...but let's keep the hyperbole under control.