If you're seeing a message like "Failed to move to new PID namespace: Cannot allocate memory" when running Chrome, this is actually a problem with the Linux kernel.
For more context, see http://code.google.com/p/chromium/issues/detail?id=110756 . In case you wonder what the fix is, the patch is available at http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=976a702ac9eeacea09e588456ab165dc06f9ee83, and it should be in Linux-3.7-rc6.