I imagine for this article the "office" was a call center bullpen type setup. It is not surprising to see increased productivity due to the reduced distractions of actually having a private personal workspace provided by the _employee_ at home.

To keep costs down it seems most companies now design for maximum bodies per square foot rather than productivity. I really wish companies, especially those with the ability to absorb some extra costs, would actually try to design for productivity and not solely cost savings.