Over at the Nintendo NSider forums, a poster documented their time with the Wii during the NYC event. Yes, late coverage, but it poses an interesting scenario all the same. Turns out, the sunlight affected gameplay for this poster during the event, affected gameplay for the worse. To quote:
"We know that the sensor bar goes all wonky when halogen lights are in the room. But did you know that natural sunlight messes it up too? That's right, if you have the sun beaming right onto the sensor bar, it doesn't work. For about an hour or so, the sun shone right into the store, the two MP3:C kiosks had to have curtains above them, and the Wii Sports Tennis and Shooting Game kiosks were unplayable since they were "shrouded" in sunlight. Later the sun went behind a building, and everything was in working order again."
Interesting, however does it actually affect most of us? With the advent of curtains (or mini-blinds, if you're that kind of person), we're hard-pressed to believe this will really hurt the experience had on the console. That is, only if you're playing on the front porch or out by the pool.