Originally Posted by
Paralytic
Many organizations will enforce a pin-lock on the phones they provide to their staff, as part of their security policy. This is enforced at the phone operating system level and typically cannot be turn off by the user.
This is precisely so, in the event that a phone is lost, possibly sensitive emails and texts are not made public.
Such policies will wipe the data on the phone if the PIN is entered (say) 5 times incorrectly and it is also possible to do a remote wipe of the data.
Of course, this doesn't help you find the phones owner
Some phones let you leave a message on the home screen, "If found, please return to blah blah blah." For iPhones and windows phones, I think through the respective "find my phone" services, you can also have it display a message on the screen.