The March 2007 edition of MSDN Magazine contains an in-depth article describing how to use WiX v2.0 and MSBuild to integrate setup into the overall software development lifecycle. You can find the article at this location:
This MSDN Magazine article is a nice complement to an older MSDN article that Rob Mensching wrote about how to use WiX to integrate setup into your development process. The main differences are that Rob's article describes how to use NMAKE instead of MSBuild to automate the WiX build process, and Rob spends more time describing the importance of treating setup the same as other source code for a software project.
If you are a setup developer or a developer on a team that produces MSI-based setup packages to deploy your code, I encourage you to take a look at both of these articles.
One additional note that I wanted to mention here - WiX 3.0 has much more seamless MSBuild integration than what is described in this MSDN Magazine article courtesy of the Votive Visual Studio add-in. I previously posted an article describing how to use Votive and WiX v3.0 and Votive to create MSI-based installers for Windows Media Center applicaitons, and the concepts described there can be adapted to all types of MSI-based installers with minimal effort.