Take it with a grain of salt, but according to anonymous sources heard by Tom's Hardware at Computex the prototypes of Intel's Larrabee are about as fast as the NVIDIA GeForce GTX 285.
According to one close Intel partner that wished not to be named, this isn't the case. We were told that Larrabee is currently only capable of performance levels similar to Nvidia's GeForce GTX 285. While this isn't a bad thing in by any measure, it doesn't quite line up with a lot of the heat that we've been told.
The partner said that with current Larrabee silicon, things may change down the line, but it did not expect Intel's graphics solution to take the high-end of the market. At the time of Larrabee's release, both AMD/ATI and Nvidia will introduce newer and faster versions of its GPUs. Despite this, it's still important to keep in mind that Intel has always been an enabler of technology, pushing other industry leaders to adopt new technology. This was the case with Intel's infamous i740.