Creating an image using text

I don't even know what this is called, so I'll take a stab at describing it.  You know those photo mosaics, where a whole bunch of little images make up one big image?  I'd like to do something similar, except using text.  To make it simple, imagine that I want to create the Adobe logo out of text where the background is black, the white parts of the logo are bright text, and the dark parts are charcoal text.  Ideally I'd like to do this in Illustrator so I can resize the final artwork.  Does this have a specific name for the technique?

Thanks!