security might be an issue otherwise when sending passwords around in the clear. do the same thing for password resets when a user forgets their password (or username, for that matter).
i mean, paypal?!
also, the 5 number password consisting entirely of numbers that was given to me when i signed on.... so that's 10*5 = 100,000 passwords to check to break into someone's account? it seems a little low. why not a 20-character password consisting of letters, symbols and numbers?
the first page i go to when logging in for the first time should be a "change password" page, not a suggested link. or just get the password from the user when they register! :-)
otherwise, though, i love the idea. command line SMS for the real world. very cool. no need to remember which phone number to call.
this way you only punish the guilty (forgetful), not everyone and their brother.