I love reading Aligorith’s blog. He is one busy little camper that not only codes an increasing number of useful tools and features, but he actually takes the time to explain them as well.
This time out, he is busy creating a new rigging tool to Transfer Shape Keys between Meshes. The goal being to have an easy (painless) way to transfer your shape keys from one mesh to a similar mesh that has been modified.
While there is a feature that currently does this, it only works if the vertex counts on both meshes match. Not helpful if you have added or subtracted geometry, which is the very problem his script aims to address.
His script is still a work in progress, but can be tested and played with at this point by going to his blog where he also has a testing suite available for download.