I am pretty sure it can be done, but i cannot get to it:
i want to create expression shapes for my character, but i would like to deform the mesh with a lattice so i don’t have to tweak all those vertices by hand.
First i would pose the basis shape.
Then add a lattice and set vertex groups for deformations.
Now i deform the lattice (even activating “apply modifier on editing cage”). Once i have deformed the mesh, i would “apply” the lattice modifier and then add the new shape to the mesh. The problem is that when i hit “apply” on the lattice modifier, it gets back to the original undeformed mesh!
I also tried duplicatong the head and using lattice on the copy, then rvk1 to rvk2 script, but no go yet whatever i try.
All i can do atm is the usual way, moving vertices by hand and adding shapes…but that’s a real pain compared to lattices deformation 
Can someone point out to a procedure to achieve this?
SOLUTION
Well it was quite easy, i simply missed the order in which to operate.
Anyway:
create your Original mesh
create a lattice and position/shape it
add lattice modifier to Original mesh
add the “basis” shape
deform lattice for 1st expression (ie smile)
select Original, edit mode and scripts>apply deformations
move created Copy to new location for visualization
select Original, then shift-select the copy, enter edit mode and scripts>rv1 to rvk2
delete copy
check shapes in orignal: voilà.
Cheers [/img]