One of Microsoft's top engineer and software architects -- Blaise Aguera y Arcas -- has left Microsoft recently to join Google. According to the NY Times, Aguera y Arcas was the person in charge of Microsoft's Bing Maps service, and was tasked with overseeing developments to the new version of Photosynth, a 3D panorama service by Microsoft.
Besides these two key services, he was also said to be involved in developmental projects that deal with augmented reality, wearable computing and natural user interfaces.
NY Time's sources that are familiar with the matter said that Aguera y Arcas will be working on machine learning at Google, but Google has yet to confirm with an official statement. Aguera y Arcas has confirmed that he is indeed moving to Google, but has declined to comment on anything other than that.
Aguera y Arcas was the founder of Seadragon Software, and joined Microsoft when his company was purchased by Microsoft in 2006. Seadragon (by Seadragon Software) is visualization technology that allows web images to be browsed smoothly regardless of size. It provides technology for several of Microsoft's other products like Silverlight, Pivot and Photosynth.
Source: New York Times