According to a rumor published by Bright Side of News (BSN), Apple may have declined to use Intel's forthcoming Calpella mobile platform and Arrandale processor in their default format. Like many of Intel's future CPUs, Arrandale incorporates a graphics core, and this has supposedly caused Apple to refuse the parts. This suggests that Intel would have to provide custom 32nm processors sans GPU in order to receive orders for Cupertino's 2010 Mac refreshes.
While BSN more or less claims it can confirm that Apple has rejected Arrandale, little is known about whether or not a modified processor is on the table. It wouldn't be entirely surprising, as Intel has worked with Apple in the past when the company requested a special-made CPU for its MacBook Air. That said, it's unclear why Apple would require an Arrandale chip without a graphics core. Naturally, being a rumor, nothing is official.