The Twilio Startup Weekend Challenge has added 5 new cities to its original list of 10, expanding the contest to include events in Athens, Paris, Corvallis, Boston, and Israel. The challenge tests startups' ability to build a project using Twilio's communication platform within a short timeframe. Teams participating in the challenge use Twilio's APIs, SDKs, and sample apps to develop their projects, with the goal of receiving timely feedback from customers through Voicify.me, managing menus online with Menu-O-Matic, or achieving personal goals with Goal Prompt. The contest continues this weekend with events in Silicon Valley, Los Angeles, New York City, Dallas, Lexington, and Cleveland, offering a chance for startups to showcase their projects and compete for the grand prize.