I'm on the fence, but I'm leaning towards "touchscreens on computers are dumb".
One one hand, everyone and their dog touches computer screens. People are always pointing to stuff on their monitors. So catering to that natural instinct makes sense. There have been touchscreens around for a long time, especially the all-in-ones from HP. Kids love them. They're useful for a lot of work applications, like shop-floor kind of stuff.
On the other hand...who wants fingerprints on a 23" monitor? What a paint to clean off. Even with the larger 10" iPad size, it's still pretty easy to clean, but a large vertical screen seems like it would look more messy. Plus, the ergonomics - I'm not going to spend an 8-hour workday lifting my arm to touch a desktop monitor.
I'd have a hard time seeing Apple jump onboard something that would make their shiny 27" iMac all greasy and streaky. Can you imagine walking into an Apple store and seeing an endless row of smeared screens? The employees would spend all day wiping them down! Although the new screens seem to handle fingerprint oils and stuff better than the old ones, so who knows. And as Apple goes more towards an iOS-based desktop OS design, maybe we'll see this become a reality. Angry Birds on a 27" Retina panel, hmm
And with the rumor of Apple switching to ARM for desktop chips, you never know...