I haven't had time to look at this yet, but talking about how people search, etc., there is a study that came out by the British JISC called "Researchers of Tomorrow: A three year (BL/JISC) study tracking the research behaviour of 'Generation Y' doctoral students" available at http://www.jisc.ac.uk/news/stories/2010/07/generationY.aspx.
A chart on p. 32 is not very encouraging. They discovered that those who cited the "main source" for their research as the "internal library catalog" was at a high of what looks like 12%, and those are the Arts and Humanties. It looks as if it goes down to 1% or 2% for another group that I cannot make out. Anyway, Google and Google Scholar are much higher.
There are several sections that seem interesting. I must point out that their report's conclusions seem a bit unsatisfying for me (at first glance) and I think some other conclusions could be drawn.
Anyway, it seems to be an important publication.