I was looking for a way to compute multilevel models in OpenMx, so I ported the Mx code in the appendix of Mehta & Neale's excellent paper (1) to OpenMx (2). As far as I'm aware, there is no working example of multilevel modeling in OpenMx yet, so I leave a link here in case someone is interested. Comments are welcome!
(1) Mehta, P. D., & Neale, M. C. (2005). People are variables too: Multilevel structural equations modeling. Psychological Methods, 10(3), 259–284.