Not everyone has the cash to spend on a 50 megapixel camera, even if such a device now exists at the consumer level. That said, it is possible to dramatically increase the amount of detail in the pictures you take with your 10-20 megapixel shooter, if you're willing to spend some time in Photoshop.
Ian Norman of The Photon Collective has created this excellent video guide to making your own "super-resolution" photos. In the clip, Norman boosts a 24MP image to 90MP, using a technique that involves taking multiple photos of the same scene, offsetting them slightly and compositing them into a single "mega" image.
If this sounds familiar, it's because some cameras can do this automatically, such as the Hasselblad H4D-200MS Norman mentions in the text version of the tutorial.
To create his super-resolution photo, Norman took 20 consecutive photos -- without a tripod. He explains that the movement of your hand is enough to replicate the sensor-shifting technology found in the H4D-200MS. Not as accurate of course, but good enough. Then, it's a trip to Photoshop:
We'll use a simple averaging (mean) filter, which will allow us to resolve detail at up to 1/4 of our original pixel size. So when we upsample, we increase the image to 4 times its original size. A 12 MP image can become nearly 48 MP, a 24 MP image almost 96 MP. There’s always a little cropping necessary because our photos will never perfectly overlap.
It's a little bit of work, but if you need the detail without blowing your wallet on a new camera, it's a clever approach. You can read more about the process over at Norman's website, or just watch the video here.
Enhance! A Practical Superresolution Tutorial in Adobe Photoshop [The Photon Collective, via Petapixel]