Two phone calls both technical, asking SQL questions and simple tree traversal questions. Also asked scenario questions and how I would analyze the data and go about solving the problem. About a week later I got an email to be brought on site. They pay for airfare, good, and taxis. Once I got there (on Friday for "Yahoo Days"), I did a coding challenge then talked to three members of the team I was applying for. There was a mixer at the end of the day where you're able to talk with other applicants and some employees. My interview was not technically intensive, but others who were interviewing said there interview was almost all coding questions.