Also, Activity Monitor, when set to "All Processes" does the same thing as ps -A.

Pretty much no harm in letting users see what the machine is running, unless someone is putting their password as a command line argument into a program that doesn't mask that out of the process listing.

Never did understand Microsoft's decision to force an elevation to see all processes in Vista. The 30+ years of UNIX users being able to see everything hasn't been a problem.