When trying to build any example from the Sources the following message is shown:

Starting C:\qt\Qt5.0.0-rc1\5.0.0-rc1\Src\qtdeclarative\examples\particles\customparticle-build-Desktop_Qt_5_0_0_rc1_MSVC2010_32bit_SDK-Release\release\customparticle.exe...
Failed to load platform plugin "windows". Available platforms are:

C:\qt\Qt5.0.0-rc1\5.0.0-rc1\Src\qtdeclarative\examples\particles\customparticle-build-Desktop_Qt_5_0_0_rc1_MSVC2010_32bit_SDK-Release\release\customparticle.exe exited with code 1

It does not find the Plugins directory, this is most likely because QT_PLUGIN_PATH is not set in the environment