Is your code in VSTA? Or are these Visual Studio solutions? MSDN explains that as of Visual Studio 2010, we no longer have InfoPath templates:
Note
Visual Studio 2010 does not include the InfoPath form template projects that were provided in previous versions of Visual Studio. You also cannot use Visual Studio 2010 to open or edit an InfoPath form template project that was created in a previous version of Visual Studio.
More information on the IP 2010 Object Model is available here.