TurboGears is designed to abstract away the common complexities of developing web applications, so that you can focus on the particular needs of your application.
TurboGears and Python are intended to help you create code that is easy to read and easy to maintain.
Kevin Dangoor built the first version of TurboGears reusing existing Python projects including SQLObject, CherryPy, Kid, and MochiKit.
Ajax and web 2.0 concepts weren't grafted on to TurboGearsthey were built in from the beginning.
The design philosophy behind Python encapsulated in The Zen of Python is important to Kevin and the rest of the TurboGears team, and you'll often hear qoutes from The Zen of Python in mailing list discussions.
TurboGears is continuing to grow into a framework that can be used by even larger and more-complex projects. SQLAlchemy, in particular, promises to make TurboGears the best dynamic language framework for people who have to work with large, complex, or legacy databases.