Tool support for mobile application development can significantly improve programmer productivity and software quality. Pegboard is a novel tooling framework that extends the Eclipse integrated development environment to support the development of mobile distributed applications. Its extensible design supports multiple application models and the orchestration of external tooling components throughout the development cycle. In this paper we describe Pegboard's architecture and implementation, and show how it improves the development experience through organization, visualization, simplification and guidance. We also discuss insights gained from interviewing software developers, including early users of Pegboard.