I updated to the CSSU from fresh install.
Gchat video call between Linux and N900 runs ok, with a couple issues with the feeds of the cameras.
Gchat video between Mac and N900 only works one way... if n900 activates the camera, the received feed from Mac (latest OS and latest flash update) is lost from N900 screen, even tough the Mac still broadcasts it.
I wonder if the camera-ui2 included in the CSSU may have affected any of the front camera settings.