Sources close to graphics card manufacturers have confirmed that they were told to expect some samples of Larrabee in Q4 2008.
Some independent sources have confirmed this schedule, but the product might actually slip to Q1 2009. Samples are going to be crucial for developers, as they will be the first to see this new GPGPU / Physics and GPU in one concept.
Nvidia and ATI can enjoy their discrete market dominance, at least for this year, and 2009 is the year when you will see the real Larrabee. We don't necessarily say that Larrabee will be an instant success, but at least it means some competition.