Now you can get your link on without the mess.
Nintendo recently announced at the Tokyo Game Show a wireless link adapter for the Game Boy Advance and GBA SP. The device will allow players to link up just as if they are using a standard link cable, only without the wires involved. The adapter's signal can reach several meters, but no specific distance is known yet. It was developed in conjunction with Motorola.
Iwata also mentioned that events or stores can have special base stations installed and connected to the Internet for players to transfer data from distant locations.
Furthermore, this new wireless link adapter will come bundled with the upcoming Pokèmon Fire Red and Leaf Green games coming out in Japan next spring. The price for the bundle is set at 4,800 Yen (approx. $40 USD). Here is a picture of the device courtesy of Watch Impress.
Update: The Wireless link will allow for up to five players to connect to each other at the same time, unlike the standard link cables which only allow up to four players. Also, sadly, games will have to specifically support the adapter.