I'm wondering if anyone knows whether it's possible (most likely with an add-in or third party app) to work out electrical creepage and clearance within an assembly. I'm dealing with some guys who design large power transformers so this is a critical issue for them.

Pro/E has a module as of Wildfire 5 - you can see how it handles it here: http://www.ptc.com/products/proengineer/spark-analysis-extension