It's kind of funny though, it seems there's going to be a Mototerminator in T4...curiously original, but is it subtle for this kind of movie? Hopefully they know what they are doing. Thinking about it, the idea seems cool, there's a sneak peak of it's design at terminatorfiles.com, and I personally like it. In fact the director mentioned something about Giger during Comic Con, and I think the design of the Mototerminator has something to do with that.
In one of terminatorfiles.com's articles marked as top secret on the T-600's appearance they've listed a number of machines that are expected to be shown in the movie including the Mototerminator. This is the list.
* Hydrobot
* T-1 Unit
* Aerostat
* Harvesters
* Mototerminator
* Classic Aerial Hunter-Killer
* Transport
* Ground Hunter-Killer
* T-600
* T-800??