Since it's launch in 2004, the WiX toolset has been completely hosted on SourceForge.net. SourceForge is fine but feels a bit clunky and a little behind the times. About a year ago I started looking at alternatives since open source hosting platforms are now a dime a dozen. In the end, I didn't find a single platform that offered everything I wanted. However, CodePlex provides Mercurial and a much better file release system than SourceForge so I decided to use those for WiX. For now bugs and the mailing list do not move (I'm still looking).
In the coming months, you'll see me putting more of an emphasis on http://wixtoolset.org as the central place to get WiX toolset information. SourceForge is kind enough to host content but its all on Linux servers. I prefer to write code in C# with ASP.NET MVC so I recently moved http://wixtoolset.org to Windows based hosting. In between working on Burn, I'll be building a site there with more advanced functionality than a bunch of static pages like we have today.
Finally, I want to mention how helpful and responsive the CodePlex team was for me. Their willingness to work with me to get http://wix.codeplex.com set up just right was a major factor in my decision move our source control and file releases there.
Now on with WiX v3.5!