From the website:
The SMS Guerilla Projector is a home made, fully functioning device that enables the user to project text based SMS messages in public spaces, in streets, onto people, inside cinemas, shops, houses…
This is the device:
If you think that laser pointer is annoying, wait till the neighborhood kids get a hold of this thingy!
http://www.troika.uk.com/troikart%20index.htm - Thanks Borel!