Super Smash Bros. Brawl and Mario Kart Wii. While the former won't offer much by way of in-game communication, the latter will in fact feature chat room options, allowing users to text it up with anyone on their Wii Friends list.
IGN reports that the texting option in Mario Kart Wii is limited to people you've swapped friends codes with (of course), and text-chatting is only possible before, and presumably after, racing matches. Text entry via Wii Remote is assumed, and IGN wagers that USB keyboards may be supported as well, as keyboard support has been included in most Wii software.
It's no voice chat, to be sure, but at least we'll be able to argue with friends over the fairness of blue shells.