I don't know a plugin for this, but you could do this with eventing. However, this wouldn't be too easy. It would help if the pictures are all of the same size and you know at least the basics in math.
But it kind of depends on what you try to do exactly. If you want the pictures to move around a lot, it won't be much easier. In that case you will most likely end up being able to check if they touch when the picture starts moving, and when it reached its targeted destination, but not halfway trough. (Well, that too is possible, but the math with just be way much harder.)
For example:
We take to images of 300×200 pixels (300 wide, 200 high)
Then we take the position of both pics, in 4 variables:
- Pos X of pic A
- Pos Y of pic A
- Pos X of pic B
- Pos Y of pic B
Check if pos X of A is less then or equal to 300 pixels away from pos X of B.
Check if pos Y of A is less then or equal to 200 pixels away from pos Y of B.
(Pos = Positions in pixels counted from the left-top corner of the screen)
If BOTH conditions mentioned above are true, the pictures touch.
This works the same no matter if you choose left top corner or center as picture placement anchor, as long as both pictures have the same anchor.