As I've pointed out before, every photon in astronomy is precious. Thus astronomers have switched to CCD detectors over the last few decades. A paper I was recently reading, published in 1991, discussed a camera with a modest 800 x 800 pixels. Barely more than many webcams by today's standards, but fairly large for the time.
Today, a decent digital camera will run around 4 megapixels. Astronomical CCDs are often much larger, and are frequently glued side by side to make even larger arrays reaching into the hundreds of megapixels.
However, even these digital monstrosities will soon be overpowered. According to New Scientist, the Pan-STARRS telescopes, which are due to go into operation soon to hunt for potentially dangerous asteroids, will be to a 1.4 gigapixel camera in March 2007! For those that aren't up on your metric, that means 1000 megapixels!