Here's a picture of the Wii's "sensor" bar in action. I'm parinoid about it, and my mom is even more so. The IR radiation you can't see:
I mean it's probably safe I guess, but still a TV remote is just a split second flash, aimed away from you, and this is a bunch of them on for hours as you play, all aimed right at you.
It's too bad, because I think the control scheme has potential for real games-like Metroid Prime 3 I think is going to be interesting. (I think that's going to be the true test for it-if it doesn't handle it well, then it's a mini-game gimick, but if the preview impressions are right, then it actually can be used for real games).
It does turn off when you're playing a Gamecube game, so I'll at least use it to finish off my last 'Cube games. I'm having a blast with Fire Emblem, and I'm looking forward to Chibi Robo even more.