early viruses
generally a wireless printer should be connected to the owners wireless network, so nobody else would be able to see it or connect to it unless they also had access to your WIFI as well.
Although some do seem to also act as their own WAP, which is kinda strange. Not really sure what is the point in that, as it means you have to disconnect from the WIFI to connect to the printer.
My neighbours have a couple of these, although they are secured.