I'm in fact interested in both.

PS from vCO:
For example using PowerCLI functions in the custom vCO actions, instead of the provided Java functions.
Since we use PowerCLI for our vSphere automation it avoids us learning and using a 2nd language.
And we could reuse part of our existing PowerCLI scripts.

vCO from PS:
Creating, starting and monitoring Tasks from a PS script.
Our vSphere automation is not done from the vSphere client but from a centralised tool (SCOM in our case).
Being able to call Task management from this PS-based environment would avoid "console sprawl" for our admins and operators.