I'm profiling my game on an Android tablet and found some GC Allocs of 56B in tk2dUIManager.Update() whenever I touched the screen.
I traced it down to tk2dUiManager/CheckInputs() and this call:
foreach (Touch touch in Input.touches)
I changed it to:
for (int i=0; i<Input.touchCount; i++)
{
Touch touch = Input.GetTouch(i);
and that made the GC Allocs go away.