It's called the R4, and it's here to rain on Nintendo's parade. The R4 fits right into the DS's cartridge slot. Data is stored on a Micro SD and downloaded via a flash drive. The R4 has a small slot that the Micro SD card goes into.
The China-made piracy device is available all over Akihabara, where retailers advertise it vaguely: "New R4 shipment has finally arrived! You know what it does! Absolutely no questions will be answered concerning this product..." or "Guaranteed for one week only! Of course we can't explain what the R4 will do..." Says a Nintendo spokesperson:
With DS games appearing on the internet within days of release, the R4 is certainly a very real threat. And something Nintendo should be keeping a closer eye on.