-G: Causes all output (and batch input for form commands with (-i) to be formatted as marshalled Python dictionary objects. This is most often used when scripting.
Of course, I'm not the first blogger to write about it, and it looks as if there are a number of people using Perforce with Python scripts.
I've always been impressed with Perforce-the-company--they were pretty cool to deal with when we needed assistance, and they've done some very non-evil things for the programming community (including providing no-cost licenses for open source projects and open-sourcing their own Jam build tool). A little digging reveals they also sponsored PyCon in the past.
I'm glad to be supporting a company like this one.