SmartQ actually has a gamepad, but it is a non-standard RF interface that no other devices I know of use... It is the one built for the SmartQ T5 II that looks like a PSX pad, if you want some pics, I can go off and find some. Unfortunately, it will not work with the Q5/7; Seems sketchy to release a branded controller and only have it work with one device.
The SmartQ website claims that the Q5 already has support for generic gamepads, which does not surprise me, as the drivers for USB Host on that SOC are very easy to implement. In fact, the unofficial port of Mer that is being tested right now already has USB host support!
It should be interesting to see where this goes, SmartQ is planning on a gaming PMP later this year, it is looking like they might actually have 3 devices using the same core, but with different cases, buttons, and screen size; So even though it started out seeming as if they were just moving on to new devices without fixing bugs, I think they want to get all 3 devices out, and have the firmware updates apply to all of them, so that they can focus on one platorm, but get the benefits of catering to 3 different markets. Very efficient, in my opinion.