Mark Zuckerberg's artificial intelligence-imbued software "butler" — named Jarvis — is now in service, and even plays with his family, the Facebook chief said Monday. Zuckerberg took on the personal project this year, devoting about 100 hours to making a system inspired by the "Iron Man" film character Jarvis as a virtual assistant to help manage his household. "In some ways, this challenge was easier than I expected," Zuckerberg said in a post on his page at the leading social network.