ohloh.net :

Over the past twelve months, 73 developers contributed new code to Google Web Toolkit.

This is one of the largest open-source teams in the world, and is in the top 2% of all project teams on Ohloh.

For this measurement, Ohloh considered only recent changes to the code. Over the entire history of the project, 97 developers have contributed.

GWT- ohloh (1412 hits)