From Rob Mensching:
The oft promised Windows Installer XML (WiX) toolset has released under a true Open Source Software license (Common Public License) on SourceForge.net (a first for Microsoft). The WiX toolset is a command-line compiler and linker for creating Windows Installer packages (MSI and MSM files) from XML source code. This blog entry kicks off a new category “Windows Installer Xml (WiX)” where I will talk about building MSI files with the toolset.
and dwellerville :
Microsoft submits open source software to SourceForge
Well, first we settle with Sun, then today we release open-sourced Windows Installer software on SourceForge.
That's right, Microsoft joins the open source ranks.. well it's a start. :)