Like the 3G MacBook Air, the updated Mac mini ships with Intel's Sandy Bridge processor and a Thunderbolt high-speed I/O port. According to Apple's press release the new Mac mini delivers up to twice the processor and graphics performance of the previous generation.
The new Mac mini comes in two desktop configurations and one server configuration:
Perhaps the most interesting development is that Apple has dropped the optical drive completely from the new mini. (Something I recommended two years ago.)
...if an app you need isn’t available from the Mac App Store, you can use DVD or CD Sharing. This convenient feature of OS X lets you wirelessly “borrow” the optical drive of a nearby Mac or PC. So you can install applications from a DVD or CD and have full access to an optical drive without having to carry one around.
The other option is to purchase Apple's external SuperDrive ($79) which works with both the Mac mini and the MacBook Air.
The new Mac mini server configuration includes a 2.0GHz quad-core Intel Core i7 processor, Lion Server, 4GB RAM and dual 500GB hard drives for $999 (US). Configure-to-order options include adding up to 8GB RAM, two 750GB hard drives, or up to two 256GB solid state drives.
...a new specification that offers ultra low-power data transfer and has been touted as opening the door to a host of new wireless peripheral devices.
The new Mac mini is the first to support discrete graphics:
The new Mac mini also makes a transition to discrete graphics on the high-end model, utilizing the AMD Radeon HD 6630M and offering up to twice the graphics performance of the previous generation. The low-end and server Mac mini models continue to utilize integrated graphics in the form of Intel HD Graphics 3000.