I just checked my 3DS and the slider actually just says "Wireless" not Wi-Fi. It is a general communications on/off switch.
If I had known that, then it would have been a dumb question, "will I need wireless communications in order to communicate wirelessly?"
So there seems to be some sort of RPG type game in the Mii plaza after you obtain a visitor. I was apparently the king, and there was some mention of hunting ghosts and stuff. I had to shut it off before the actual game started, but it was... unexpected.
In other news Street Fighter 4 has become my favorite 3DS game. I expected to quickly test out the touch-macro system (in case you could map entire combo strings to a button, no you can't) and got completely addicted to the arcade mode, and by arcade mode I mean being challenged constantly by people over Wi-Fi. I don't even know if BP and PP have any use, but it's fun seeing numbers go up.
I'm having a hard time getting into Ghost Recon. I'm only on level 2, but combat seems to drag a bit, and the tutorials are either worded tediously, or are simply too wordy, or something. I am hoping the pacing smooths out once the game starts rolling.