[I though that was already ticketed but couldn't find it.]
A bunch of us have been seeing the following problem: run gazebo with a certain world and get gzclient with an empty 3D view. No ground plane, no sun, no robot, just clouds. If you leave that running and start a second instance of gzclient, the second one works fine. Also, if you manipulate the world in the second gzclient (e.g., drag the robot, insert an object), the updated models start to appear in the original gzclient. It appears as though the first gzclient missed the "initial state" message and only gets diffs thereafter.
My machine is currently reproducing this problem reliably, as is John's. I'm using gazebo-prerelease-1.4.5 and drcsim-2.0.0 from debs. To reproduce:
. /usr/share/drcsim/setup.sh roslaunch atlas_utils atlas.launch
I don't get the problem just running gazebo.
Giving high priority to this in the hopes that we can figure it out for Gazebo 1.4. The workaround is easy enough, but the behavior is annoying and non-intuitive (the first I encountered it, I thought that something had gone terribly wrong and spent time verifying compatibility among versions of everything before somebody told me that it's a known issue and that I just need to restart the client).
Happy to help debug if I'm pointed in the right direction.