I've seen too many commandline programs dumping help output to stdout.
Please, use stderr for non-nominal output messages. All error messages, help text, etc. should be directed to stderr. This way the users can use pipes to get the output they want.

del.icio.us
Digg
Google bookmark
reddit
Simpy
StumbleUpon
Furl
Newsvine
Technorati
Tailrank