It was noticed in the kernel source for tegra3 by someone on irc the other day that the companion core can be accessed from userland
root@android:/sys/kernel/cluster # pwd
root@android:/sys/kernel/cluster # cat *
the 2 in the above output is LP2 power mode, the LP is low power and when the screen turns on it turns to G status, meaning geared performance or something like that ...
Thought id add it for completeness as post 1 mentioned its not accessible or visible