From within Lightroom 3.6 Beta, PP Studio v10 appears just fine as an "Edit In" choice.
For PS CS5.1, PP Studio v10's installer did not handle the installation of the Plug in file properly! PP Studio v10's Photoshop Installer automatically saw PS CS5.1 and installed PSFilterPPLauncher.8bf into the C:\Program Files\Adobe\Adobe Photoshop CS5\Plug-Ins subdirectory.
On my system, PS CS5.1 is installed on the K: Drive in the K:\Adobe\Adobe Photoshop CS5.1 subdirectory.
In order for PS CS5.1 to properly show Anthropics > PP Studio v10 under the Filter pulldown menu, and for Portrait Professional to appear on PS's Help > About Plug-In list, the PSFilterPPLauncher.8bf file had to be moved to the K:\Adobe\Adobe Photoshop CS5.1\Plug-ins directory.
Also note that the PSFilterPPLauncher.8bf file is the only file in the root of that subdirectory. It is not contained in any Anthropics nor Portrait Professional directory within K:\Adobe\Adobe Photoshop CS5.1\Plug-ins! This is not the convention for all the other plugins. They are contained in a product or company named subdirectory below, the K:\Adobe\Adobe Photoshop CS5.1\Plug-ins subdirectory.
For PS CS5.1, PP Studio v10's installer did not handle the installation of the Plug in file properly! PP Studio v10's Photoshop Installer automatically saw PS CS5.1 and installed PSFilterPPLauncher.8bf into the C:\Program Files\Adobe\Adobe Photoshop CS5\Plug-Ins subdirectory.
On my system, PS CS5.1 is installed on the K: Drive in the K:\Adobe\Adobe Photoshop CS5.1 subdirectory.
In order for PS CS5.1 to properly show Anthropics > PP Studio v10 under the Filter pulldown menu, and for Portrait Professional to appear on PS's Help > About Plug-In list, the PSFilterPPLauncher.8bf file had to be moved to the K:\Adobe\Adobe Photoshop CS5.1\Plug-ins directory.
Also note that the PSFilterPPLauncher.8bf file is the only file in the root of that subdirectory. It is not contained in any Anthropics nor Portrait Professional directory within K:\Adobe\Adobe Photoshop CS5.1\Plug-ins! This is not the convention for all the other plugins. They are contained in a product or company named subdirectory below, the K:\Adobe\Adobe Photoshop CS5.1\Plug-ins subdirectory.