I took a sample of the Google Plus graph and loaded it up in to the excellent Gephi graph rendering package. Due to the simple manner in which I crawled the data, this doesn't represent a true breadth-first crawl of the graph (rather it captures the random set of in and out links that appear on a user's profile page). However, what is interesting is that there is a clear tightly connected component that is distinguished from a more dilute area. I suspect, without any real investigation, that this is the core area of Google employees and some of their immediate connections as well as alpha users. This is complete conjecture, though.
In capturing this data, I also observed the complete in and out degree of each node. The top ten that I came across where (in order): Mark Zuckerberg, Vic Gundotra, Robert Scoble, Tom Anderson, Matt Cutts, Markus Persson, Pete Cashmore, Thomas Hawk, Evan Williams and Om Malik with links ranging from 456k to 33k.
Finally, I noticed that 48% of users haven't yet posted.