For kicks, I was trying my XF forum last night via my Wii, which uses a custom version of the Opera browser. Navigating the forum works OK, even if the links are a bit small. But, I could not reply to posts--I could not get focus over to the editor window, no matter what I did. "Typing" on the Wii is a pain, as you do it from a screen-based keyboard; this activates when you focus on any text area (an <input> or <textarea> in a form in other words).
As I mention in the title, the market for XF usage on the Wii is probably one person (me) in billions (the world population), so I wouldn't urge anyone jump on fixing this one. But thought I'd make you aware of it anyway. I'm willing to be the test guinea pig if you should decide to look into this.