See the two screenshots displaying a concrete (cube1) and a wooden cube (cube2). Each one has its own material which references its own uv map.
Now when I switch from cube to cube (object selection and then edit mode) the image in UV/Image Editor's background never changes. But the unwrapped faces are updated correctly and 3DView (material and rendered) is also working.
This challenges me for a few days now. Any help is greatly appreciated.
Blender 2.78c Cycles
Update: This answer deals with the active image within cycles. Its simply not implemented that image view displays "the best" texture for an object but always the last image used, even if it belongs to another material. Set active image node with python
Update2 Interesting: As stated here https://developer.blender.org/T34978 the ImageView is completely decoupled from the material. This was a bugfix in 2013.