Maybe 10 months ago I downloaded Orca to tinker with an MSI file on a setup and installation project. While it was nice to twiddle inside of the MSI tables with Orca (ever read the story behind Orca?), the experience is nothing like Wix, which can decompile an MSI file into XML. This is great, because I can now check installations into a source repository as a text file and do DIFFs if needed.
Of course, you can also compile an XML Wix file into an MSI, which means no more fiddling around in a GUI to make changes in an opaque file for you. For some reason Visual Studio setup projects always worry me because I don’t know exactly what I’m changing when I do a save. I always feel there is something sinister at work in the background.
Even more interersting: the project has been open sourced by Microsoft. It is definitely a strange feeling to go to SourceForge to download MS bits.
That leaves DTS packages as the only other binary pieces under source control that I'd rather see as XML.