but before it worked i had to comment out line 173-176 in  glsl_geometry.ccp
got the error "cannot load shader now" didnīt really understand why

because you tried to load the shader when no openGL context existed, and glew was not yet initialized. loading of shaders is deferred till rendering really starts, so it probably shouldn't bail out as an error.
in this case i get "cannot load shader now! deferring till later..." and when the rendering starts the shader worked

however, initialized glew is crucial for shaders, as we don't know whether the system actually supports openGL-2.0 (or 2.1 for geom-shaders) without it.
just uncommenting the checks is a bad idea, if you want to not have crashes on the majority of gfx-cards out there...
did another try !GLEW_VERSION_2_0 && !GLEW_ARB_geometry_shader4 work ŋ? GLEW_VERSION_3_0 gives also the error
GemWindow Activate err = 0
GEM: GLEW version 1.5.1
GEM: Start rendering
on mac osx 10.5.6

Matthias