I have a prediction for next year’s Christmas season: the big gift will be WiFi-enabled flatscreen televisions with built-in media codecs. That is, the TV will include the functions of a media extender, and play things like DivX, Flash, etc. It will speak to your wireless LAN (802.11n) and will be able to see your files on Windows shares. (Thus bringing rabbit-ears back to your television. Yay!)
In other words, you won’t need a dedicated box anymore, it’ll all be in your TV.
They’ll be expensive as all get-out next year, available only in big-box stores. The year after they’ll hit Wal-mart and Target and be more reasonably priced.