QuickBuild 2.0 introduces concept of proof build to build and test your uncommitted changes at server side. With proof build, the risk of polluting SCM with bad code will be reduced to minimum as developer can submit a proof build and only commit their changes if the proof build is successful.
The source code used to generate a proof build is first checked out from trunk of the SCM, and then patched with uncommitted changes collected from project work area at user's desktop (with the help of user agent which will be mentioned later).
For distributed version control systems, instead of verifying uncommitted changes, proof build is used to verify local commits which will be pushed to central repository.