coords = array.array('f', [0.0]) * len(me.verts) * 3
m.verts.foreach_get('co', coords)
the reverse works with set also.
currently works for python buffers or sequences (slower)
Quick speed test with 1,179,654 verts.
*foreach_get*
list 0.377
array 0.032
py 10.29
*foreach_set*
list 0.184
array 0.028
py 9.79
where python was done like this...
----
i= 0
for v in m.verts:
co = v.co
l[i] = co[0]; l[i+1] = co[0]; l[i+2] = co[0]
i+=3
----
some of the error checking here needs to be cleaned up to account for different invalid bad inputs.