NVIDIA's road into mobile may have just taken an unwanted (if temporary) detour. The company confirmed at week's end that its Mobile Business Unit's General Manager Mike Rayfield quietly left the company on August 24th to join another firm, although we don't know whether he's headed to a rival or in another direction altogether. NVIDIA also hasn't yet said who replaces Rayfield at the helm. No matter who takes his place, the departure is a significant blow to the crew in Santa Clara: the executive had been heading mobile development at NVIDIA since 2005, before anyone really knew the company was interested in the handheld space, and helped make the Tegra name synonymous with fast Android phones and tablets like the One X and Nexus 7. There's little doubt that more than a few competitors would like to have him onboard.