Not Proof of Stake.  Currently we are Proof of Work specific.

From https://en.bitcoin.it/wiki/Merged_mining_specification for definition...

Auxiliary Proof-of-Work (POW)
a.k.a "AuxPOW". This is the way that merged mining can exist; it is the relationship between two blockchains for one to trust the other's work as their own and accept AuxPOW blocks.
Merged Mining
The act of using work done on one blockchain on more than one chain, using Auxiliary POW.