what version of pymel are you using? the only thing that i can think of is that either you're using an old version or somehow the version you're using has bad caches for 2011. have you updated to 2011 hotfix1 or hotfix2? i'm fairly confident that if you use the native pymel with 2011 you won't have this problem, but that isn't really a solution. i can confirm that pymel.core.camera() 1.0 is working properly in both 2009 and 2011.
-chad -- http://groups.google.com/group/python_inside_maya
