A thought. Since the Google tool bar sends back information about websites that the end user visits could running a Google Adwords (thinking that a larger percentage of these surfers would have the google toolbar as opposed to a banner ad somewhere else) assist in pagerank / spidering?
I don't see how running an adwords link in Google affect pagerank. I doubt Google counts links from within its database for link popularity, or I have never encountered evidence of this. If I'm wrong, someone please feel free to correct me.
As for spidering, that's another story. Does anyone know about this?