I have a process which leverages PSINFO via. XP_CMDSHELL and unfortunately this functionality no longer works under SQL2012. oddly, I could not find any information regarding a behavioral change that would effect this functionality but it appears to no longer perform as expected.
As an example:
EXEC xp_cmdshell 'Psinfo -d disk'
Returns the volume information correctly on all prior SQL Server versions however, it simply hangs on SQL2012. The initiating SPID will simply wait indefinitely on PREEMPTIVE_OS_PIPEOPS.