An Nvidia partner confirmed to us that Apple was the first to receive samples of Nvidia's Ion platform, which we covered extensively during CES. In fact, Apple received prototype units long before Nvidia partners who opted to work on Ion. We're told that some partners still only have blue prints of Ion.
Apple's MacBook and MacBook Pro unibody notebooks already use Nvidia's 9400M GPU for graphics duties, and this GPU is precisely what Ion uses. The GPU is capable of full HD video decoding and also supports Nvidia's CUDA technology for more general purpose computing. Pairing up with the 9400M is Intel Atom 330 processor. The Atom 330 runs at a clock speed of 1.6 GHz on a 533 MHz front side bus and has two times the execution resources and L2 cache as the Atom 230.
Because of the size of the Ion platform, we can expect the new Mac Mini to be even smaller than the current generation unit. Our source also informed us that Apple will be launching the new Mac Mini sometime in March of this year, around the same time that CeBit happens.
At this time, no pricing information has been confirmed. But judging from Apple's release patterns, we can expect the new Mac Mini to cost roughly the same as the current generation of Mac Mini when they initially launched in the $500 to $700 range. Nvidia itself stated previously that it expected Ion products to start at roughly $400.
Update: We had a discussion with Kasper at AppleInsider on this detail, and according to Kasper, Apple may be using Nvidia's Ion platform for an updated Apple TV. This seems highly plausable. At this time however, neither we nor AppleInsider are absolutely sure where Apple will be using Ion, but an Nvidia partner explicitly said Apple has Ion for Mac Mini.