Not that any of you actually use the feature, but starting next month the Wii won't be supporting MP3 playback. Announced as part of some changes due for the Photo Channel, in future the console will only support AAC playback. This will affect current Wii owners during either the next system update, or if you choose to download the new Photo Channel 1.1, which will be available in December. Updates to the Photo Channel seem minor (all it says is you can replace the Channel icon with a pic of your choosing), so this sounds more like a move prompted by whatever copyright/legal reason has Nintendo worried this week.
The Photo Channel Will Change [Nintendo, thanks Leo!]