HP Printer Fun is an application for you BlackBerry, that let's you change the text of an LCD display on any HP LaserJet printer? What could you do with this awesome power?
I don't know. The application works with every HP LaserJet printer that I have come across. It is possible that there are some that won't work with HP Printer Fun, but I doubt it. One way or another, the price is free, so the cost of failure is 20 minutes of your time.
Some IT departments have an attitude that if the network is not locked down like the SuperMax prison camp, then something is amiss. If that's the case, I wouldn't tempt the fate. Can IT detect these messages to the printer? Very unlikely: to the network, it looks like someone is printing something out.
If you don't know how to find the IP Address of the printer, this video explains it all.