This Ork Big Trakk with Supa Kannon was part of the Ork Shanty Town display at GamesDay 2010.
I have been making my own Big Trakk and it’s a nice if somewhat complicated kit to put together. I am not going to arm it though with the Supa Kannon and will probably use a “normal” Kannon. According to Tony Cottrell at the Forge World seminar at GamesDay 2010, it would appear that Forge World have “finished” with the Orks for a while and will be doing lots of other stuff before they return to the Orks (it at all).
Of course what we still have to see from either Forge World or Games Workshop is a new buggy or wartrakk. There are images in the Forge World Imperial Armour book of a new design of a buggy, but so far no real concrete evidence that any new model is going to be released.