When compiling gtest master as a subproject I get a bunch of warnings like this:

CMake Warning (dev) at test/gtest/CMakeLists.txt:3 (project):
  Policy CMP0048 is not set: project() command manages VERSION variables.
  Run "cmake --help-policy CMP0048" for policy details.  Use the cmake_policy
  command to set the policy and suppress this warning.

  The following variable(s) would be set to empty:

    PROJECT_VERSION
    PROJECT_VERSION_MAJOR
    PROJECT_VERSION_MINOR
    PROJECT_VERSION_PATCH
This warning is for project developers.  Use -Wno-dev to suppress it.

I don't get this warning if I build gtest 1.7.0, likely because it incorrectly calls cmake_minimum_required() after project(). That's incorrect but it happens to be better in my specific case. However, I think the proper fix would be adding cmake_policy(SET CMP0048 NEW) to your cmake files. The warning is about PROJECT_VERSION and related variables getting unset automatically, but I don't think you're using any such variable so it shouldn't make any difference.