Why doesn't the Web Platform installer recognize that SP1 is already installed for VS2010?

Question

I upgraded the Microsoft Web Platform Installer (WPI) to version v3.1 today to install the MVC 3 Tools update. I noticed that Visual Studio 2010 SP1 is not marked as “Installed”, but I already installed it through WPI last week. Does anyone know if this is a problem with WPI, a non-recognizing and installed component, or if something really changed in SP1?

Additional Information:

I read another article that referred to this reg-key as an indicator of the SP level:
Key: HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ DevDiv \ vs \ Service \ 10.0 \ procore
Value: SPName = SP1

Answer 1

Chris Sfanos (PM web platform installer) writes 04/20/2011 12:05 PM in this web platform installer under http://forums.iis.net/t/1177387.aspx : "I will follow the VS SP1 team, which owns the WebPI package for more details. " Since then, Chris has not provided newer information, so it seems that Microsoft knows about the problems, but so far has no means.