>What does this mean for you as a Photoshop user? That working with large images on Windows Vista64 machines will be a lot faster. Don’t expect everything to be faster in 64-bit, though, as Photoshop architect Scott Byers wrote in 2006.
So why won’t the OS X version of Photoshop CS4 be 64-bit when the recently posted Lightroom 2.0 beta is 64-bit? All “older” Mac applications such as Photoshop, After Effects and even Apple’s Final Cut Pro and iTunes are developed on the Carbon framework. Last year Apple canceled the 64-bit roadmap for Carbon so only applications built on the newer Cocoa framework will be able to be 64-bit-enabled, even though Steve Jobs in 2006 said “You can have fully native 64-bit UI Carbon or Cocoa applications.”
For more in-depth explanations (and conspiracy comments) please see Adobe Product Manager John Nack’s blog. There’s also an FAQ: Plans for 64-bit processing support in Photoshop (PDF.)
It’s still unclear if Photoshop CS4 will run on Windows XPx64 or if Vista64 (oh, the horror!) will be required.