[GRASSLIST:4673] Outputing values of neighboring cells in a DIFFERENT layer

[Jason Horn]

I'm looking for a little advice.  I need to output some cell values by 
examining two raster layers.  I need to know the values of neighboring 
cells (very much like what r.neighbors does).  However, rather that 
getting the values of the neighboring cells in the same layer, I need 
the values of the neighboring cells of the corresponding cell in a 
DIFFERENT layer.

For example: I have two layers A and B.  I'm interested in cell (10, 
10) in layer A.  I'd like to output the values of the neighboring 
pixels from the corresponding cell (10, 10) in layer B.  I want to do 
this for every cell that is part of a particular phenomenon in layer A.

r.neighbors is close, but not quite it.  I need the ability to get the 
values of neighboring cells from OTHER layers.  Does anyone have any 
ideas?

Thanks for your ideas!

Jason