HotHardware - If you're trying to configure an iMac system to arrive in time for the holiday season, you'll have to cap your storage at 1TB. Next day shipping is available on iMacs with a 1TB mechanical hard drive, 256GB solid state drive, or 1TB HDD + 256GB SSD from the Apple Store, but if you choose one of the 2TB HDD options, you'll have to wait 5-7 weeks for it to ship. That would put the arrival date at anywhere from the middle to end of January.
OWC: "In examining the 2011 27″ iMac’s viability for our Turnkey Upgrade Service, every workaround we’ve tried thus far to allow us to upgrade the main bay factory hard drive still resulted in spinning fans and an Apple Hardware Test failure. We swapped the main drive out (in this case a Western Digital Black WD1001FALS) with the exact same model drive from our inventory which resulted in a failure. We’ve installed our Mercury Pro 6G SSD in that bay, it too results in ludicrous speed engaged fans and an AHT failure. In short, the Apple-branded main hard drive cannot be moved, removed or replaced."
Engadget - The heaviest of heavyweights in the all-in-one field has seen another update, another batch of new internals to liven up the aging (but still classy) chassis. Apple unveiled its latest iMac refresh last week, surprising nobody with a new selection of AMD Radeon HD graphics cards, quad-core Intel Sandy Bridge processors, and solid-state storage options, all designed to do one thing: go faster.