The entire project is licensed under the Apache License 2.0, which is a permissive license, so there is no issue using the software in any kind of application, commercial or non-commercial. The reason for this license is that it is the one used in the runtime library (which is licensed by Nikhil Kothari).
The compiler has been developed by Erik Källén, www.erik-kallen.se
Linq support is achieved with the help of Linq.JS by Yoshifumi Kawai.
The code generator for jQuery UI was initially written by Ivaylo Gochkov.
This project, in various places, uses an ECMAScript grammar by Xebic Inc. (This grammar is actually BSD-licensed, but I have permission to redistribute it under APL2 as part of Saltarelle Compiler).
Issues (both compiler and library ones) are tracked on GitHub.
The source code is available on GitHub.