AaronRogers.com: "Most of us will remember Wednesday, April 13th 2005. On that day, Tim Schuerewegen released the driver and application necessary to allow anyone with a Nintendo DS, a GBA flash cart, and a supported wireless network card to load any homebrew demo/app on their DS. You already had the ability to do this with a PassMe device, but now can do it wirelessly!"
Follow the link to see if you're one of the lucky ones with the appropriate chipset. OR drop about $50 on a compliant wifi antenna card.