Nintendo more or less owns the handheld market at the moment. Now Nintendo owns part of the handheld market even when it's not on a hendheld system it owns. Huh?
The company has been granted a patent for "software implementation of a handheld video-game hardware platform"---better known in layman's terms as an emulator. The patent, number 6,672,963, was granted in January, having been applied for way back in November 2000. The patent specifies "low capability target platforms," such as cell phones, PDAs, and screens built into the back of airline seats. If you can play a Game Boy game on those devices and not notice a significant difference, reasons Nintendo, you're less likely to buy a Nintendo unit for your next big trip away from home. The patent gives Nintendo a way to stop potential piracy through iron-clad legal means.
Already, Canadian developer Crimson Fire---which has been working on a GBA emulator for the Tapware Zodiac---has been served with a cease-and-desist notice. To read the patent yourself, look it up on the web at uspto.gov
---GamePro June 2004