Insight Media calls them pico-projectors (I think I like microprojectors better. I hope someone thinks of a better name by 2012).
I'm not doubting this will come to market and eventually become popular. Business users will love it, enabling them to give private impromptu presentations to a clients over lunch (using a white table napkin perhaps as the screen). High school and middle school teachers will hate it when naughty teens use it to beam inappropriate videos at their white board during the middle of a lecture.
For cell phone users who check their email in the theater half way through "The Other Bolelyn Girl" or take a call in a really loud voice for everyone to hear in a two table radius at an otherwise quiet, intimate restaurant, be warned. When miniprojectors, pico-projectors, whatever you want to call them start getting bundled into mobile devices, people with that mentality are going to take obnoxious behavior to new depths.