Shige Honjo, who was Nest's VP of program management, is one of them. He was also Nest's second-ever employee. Shige left Apple along with Nest's co-founders Tony Fadell and Matt Rogers when the company was first getting going. It's not clear what's next for Honjo.
Scott Mullins, the other employee who's leaving Nest, served as a senior engineering manager. But he isn't totally departing. He's planning to stay within the Alphabet family, moving over to the "Project Aura" team, focusing on the next iteration of Google Glass. He'll still report to Tony Fadell, Nest's CEO, who runs the Aura team independently.
It's not clear what, if anything, sparked the departures, but Nest has been in the press a lot recently.
Employee morale is down overall at Nest due to some product issues and a somewhat tough working environment. Earlier in March, Nest came under fire when Fadell was quoted as saying some not-very-nice things about Dropcam employees. Dropcam was acquired by Google for more than $500 million and worked closely with Fadell and the Nest team. Dropcam's founder responded by calling Fadell's comment "blatant scapegoating."