Contrary to common belief, the volume of face-to-face interaction decreased significantly (approx. 70%) in both cases, with an associated increase in electronic interaction. In short, rather than prompting increasingly vibrant face-to-face collaboration, open architecture appeared to trigger a natural human response to socially withdraw from officemates and interact instead over email and IM.
This matches my own experience. I share an office with three other people and it's pretty quiet, but we do talk sometimes. When I had to move to an open space area for two weeks during some construction, I was shocked at how silent it was! They didn't even say "Good morning" to each other!