Applied via Twitter website for summer internship. They contacted me about a week and a half later, very nice recruiting team. They said I would have to go through 3 phone interviews (and if you're in the area, the last one is you being invited to their offices). Had a one hour phone interview with one of their employees. Had a bit of technical questions, and questions relating to my previous projects. Then was asked what I thought about Twitter and their mobile app. Ultimately was declined about 5 days later, but it was still a good process nonetheless.