I actually didn't hear anything about this until it was reported by various sites and on the news. Even then it wasn't really that widespread of a problem. But when it was brought to everyone's attention, MS did basically what Nintendo is doing now.

My friend bought his Wii on the release (december 8th). The wrist band shipped with his console is the same as the one he got with Wii Play. I don't know if it's the new thicker one or the old thin. I hope he wont get any problems, he can hold onto the controller without dropping it while playing but unfortunately the same cannot be said about his little brother.