Crafty 3DS tinkerers have found a way to disable the system's region locking without modifying the system's hardware.
The installation, which involves editing the hex values of some files, is somewhat fiddly and does require the use of a potentially illegal (depending on where you live) DS flashcart in order to apply the necessary tools.
This region unlocking patch does not enable piracy on the 3DS, however.
Some techincal knowledge is required to install the patch, too. Full instructions can be found GBATemp (via Kotaku) for the brave, and we'd advise not to start the process unless you're particularly confident doing so.
Nintendo's 3DS is the first of its handheld consoles to impose region locking, which means that players are unable to import and play titles from other regions such as Monster Hunter 4, which is currently only available in Japan and as of yet has no release date in the US and Europe.