Snjb, you mentioned how you have to relogin from the server to the server again to be able to use devices properly. If you log into any machine via ssh where you want to compute, sou have to set the COMPUTE=:0 environmental variable in .bashrc, or just export it, then CAL will see all devices properly for computation. No need to re-login or do another ssh.
The reason why I post reply as seperate thread, is becuase the 'reply' button cannot be clicked. You posted a too long code line, and there is no scroll bar for the entire page, only for the code segment. This issue has been present under firefox (dunno about other browsers) for the past year, even with 4.0 RC right now, so I guess it's html issue. Please correct this bug, because Snjb's topic cannot be continued, becuase nobody can reply. (At least I can't)
Hope that helped.