A few times since January 2009, I’ve mentioned “Marble”, a secret UI design project at Apple which I believed was a new system-wide theme for Mac OS X. E.g.: my MWSF 2009 predictions, and my WWDC 2009 predictions. Ends up I was wrong about what “Marble” is — and in fact, it was announced at WWDC 2010 this month. It’s Xcode 4.
Xcode 4 is still in beta, Apple doesn’t have screenshots available, and what was shown at WWDC 2010 is covered by NDA. But if you have a developer account, you can get a tour of the new interface by watching the Developer Tools State of the Union session. It is, to say the least, a major overhaul — primarily focused on doing more within a single window, even going so far as to bake Interface Builder into Xcode itself. According to several informed sources at WWDC, that’s the “Marble” project.
Another correction I gleaned at WWDC is that the iPad’s OS 3.2 was not, as I suggested in a footnote here, developed by a team working in secret, apart from the main iPhone OS 4 team. The iPad’s OS 3.2 is indeed a separate fork — 3.2 was never meant for use on iPhones or iPod Touches, and 4.0 will not be available on the iPad. But the team wasn’t separate — those working on 4.0 knew what was going on with the iPad and those working on the iPad knew what was going on with 4.0.
As for why this week’s new iOS 4.0 doesn’t support the iPad, it’s simply a matter of timing. Apple wanted to start selling the iPhone 4 this month, June. The iPhone 4 required iOS 4. And it took less time for iOS to support only iPhones and iPod Touches than it would have to add support for iPads, too. I still believe that iOS version 4.1, planned for this fall, will be the release that unifies support across all shipping iOS devices.