Found some new info on animal crosging wild world's Wi-Fi network:
Wireless Functions:
DS Local Area Network
When players are within wireless range of other people who have Animal Crossing: Wild World, they can travel to one other's towns. One person will be the host and open up his or her town gate to visitors. Up to three others within range can exit their town gates to travel to the host's town, where they can do all sorts of things: fish, write letters to townsfolk, shop at the store, cut down trees, anything. Up to four players can interact in real time, communicating with text messages and emoticons. (All players must have game cards for multiplayer mode.)-After players visit another town, the following events may take place.
-One of the characters in the town they visited might move to their town, and a character from their town might move to the town they visited.
-"Bottle mail," a bottle containing a letter written by someone in another town, might wash ashore in their town.
-Constellations created by someone visiting their town might appear in the night sky.
-This mode is open to anyone in Local Wireless range