It looks like just the core applications support the keyboards so far but I think as time goes on, more and more applications will support USB keyboards.
I plugged in the Dell USB keyboard I normally keep plugged into the XBox and was surprised to see that I could type inside the various Wii menus. As I have browsed various sites today, other people have mentioned USB keyboard support working. I hadn't tried it until just after I upgraded the Wii, so it was a bit of a fluke for me.
At age 32, I get to get all 4 wisdom teeth taken out later this month. Right now, one of them has a lovely infection behind it, so I am on antibiotics and have a good 100+ temperature fever going. As a bit of a pick me up, I rented
Mario Strikers Charged, which is essentially Mario Soccer, or in Europe, football. Very fun game so far. I'm not very good at it but it is a fun game. I'm not sure if I will buy it eventually or not, especially now that I have access to the Virtual Console games. Metroid is supposed to debut on the Virtual Console next Monday apparently.