It’s true:

Apple is making a transition to Intel processors because Jobs says Intel delivers better performance per watt, and IBM has let them down with no 3 GHz processor and no PowerBook G5. The transition will last “a few years” starting next year at this time with the first Intel-powered Macs.

According to Jobs, Apple has secretly been working on Intel compatibility for five years. (Ironically, what many rumors had speculated when Apple first made the transition to the NeXT operating system, which always ran on Intel.) He says the entire WWDC keynote was presented on Intel OS X. The operating system was always designed to be cross-platform, and every Apple app has been cross-platform tested, from iPhoto to QuickTime to Dashboard. (read more for details)

Compatibility Tweaks Required: This transition won’t be without technical hurdles. Code will have to be tweaked and recompiled for Cocoa and Carbon. That could be bad news for the Mac music developer community, which has just expended lots of energy just dealing with the OS X transition — now they’ll have to make sure code works on Intel, and Apple will have a leg up with its Logic, GarageBand, and Soundtrack products.

But, the good news is, it does sound like Apple is going to work to make things easier: the new Xcode can build universal binaries that work on both processors, a feature that was already in NeXTStep according to CDM’s Lee Sherman. And even better news: Xcode 2.1 is available TODAY. (Question for your developers: what if you’ve been on Metrowerks, etc.?)

How quick this could be: Wolfram Research ported Mathematica to the new platform just two hours after clicking a checkbox in Xcode. (Of course, I remember similar claims about Carbonization with Adobe at a previous keynote, but let’s hope this isn’t smoke and mirrors.)

Rosetta will translate PowerPC binaries to Intel in real time. Jobs: “Most users won’t know they’re running it,” says Jobs, and has demos with Microsoft apps, Quicken, and Photoshop. (That’s good news, because the MS apps require lots of compatibility with cross-platform and legacy code.)

3.4G P4 Mac: Here’s a day we never thought we’d see: 3.4GHz Pentium 4 Macintosh. That’s the specs for the developer-only Transition Kit machine, US$999 for developers (who apparently have to return the machine — huh?). Microsoft is onstage at the expo committing support for this and Mac-first and Mac-only features for its software. Adobe’s Bruce Chizen: great news, Apple, but “what took you so long?”

CDM’s Lee Sherman contributed live from WWDC for this report with editor Peter Kirn.