I've been playing Smash Bros. Brawl lately, and I noticed quite a bit of controller lag while navigating the menus and during matches. I only play OFFLINE, so it has nothing to do with Nintendo's online servers.
The lag mainly occurs when I'm holding down a button. The character will do this jerky "start-stop-start" movement. Sometimes I get a "double press" when tapping a button on the menu screen. This happens with both of my Wii Remotes.
The lag never occurs in any other Wii game I played.