We asked our colleague over at Download Squad, Matt Heerema, for a designer's eye view on the new iMac 27" model.
Designers everywhere will rejoice at the announcement of the 27" iMac. With a resolution of 2560 x 1440 pixels, you are just 160 pixels shy of a full, pricey 30" monitor (2560 x 1600). My current design setup (17" MBP, 24" Cinema display) nets me two 1920 x 1200 screens, though only one of them is really useful at a time.
My current Photoshop or Fireworks workspace occupies about 1500px of screen (with however much height is available at the moment). The 27" iMac means I would have a spare 1000px to have a browser with a full-width Web page open for reference, or possibly my coding environment (usually Textmate or Coda), for which 1000px would definitely be sufficient.
This side-by-side workspace would mean massively efficient flow. Combine that with the intense specs of the iMac (quad-core processor & boatloads of RAM, anyone?), and you have the ultimate designer machine. Also: The 27" will handle DisplayPort input as well as output, allowing it to double as an external display for yet another computer, in a pinch.
Now, where did I put my credit card?