One could argue that OS X already has a basic implementation of this with Exposé - work down at the single window level, then zoom up to the all-windows view, zoom back down, etc. It even combines with Spaces well - you can trigger both Spaces and Exposé at the same time to scour through windows on all the desktops.
There's also a feature exactly like the type of zooming described in the blog post and demoed in the flash prototype, you can turn on Zoom from the Universal Access Preference Pane, but it's something that I typically only use to check colors or graphics when designing layouts, it's not nearly as usable as Exposé + Spaces.
There is lots of research on zoomable user interfaces. A variation is detail-in-context interfaces where the points of interest are magnified while the rest is compressed. The OS X icon bar is a good example. Check out
http://pages.cpsc.ucalgary.ca/~sheelagh/wiki/pmwiki.php?n=Ma...
(contains many references to ZUI research as well) It's been suggested to use a trackball with your left hand to zoom in and out while keeping the mouse in your right hand (vice versa for left-handed people). I'd like to see that happen.
This would be killer on the iphone because with the accelerometer you could physically move the phone around the surface of your virtual desktop to reveal different areas of it.
There's also a feature exactly like the type of zooming described in the blog post and demoed in the flash prototype, you can turn on Zoom from the Universal Access Preference Pane, but it's something that I typically only use to check colors or graphics when designing layouts, it's not nearly as usable as Exposé + Spaces.