The evidence from folk who study this seems to differ from this.
The world is full of anecdotes about how much better things are with the newer technologies - yet I can very little evidence that this is true. I know I'm really good at fooling myself about my own productivity. I don't imagine I'm unique there ;-)
And my personal anecdotal experiences over the years (including recent ones ;-) is that you can really ramp up productivity by getting everybody on a distributed team in one place. Even when everybody is normally skyping / IMing / whatever.
Not to mention that most productivity studies are bunk.
The real reason many so many managers resist remote work is because, effectively, they want a fiefdom, and the exercise is often about empire building. An empire of a bunch of Google Talk connections isn't as impressive as a bunch of huddled seat warmers.
Need to have a concentrated task force from 5 various departments? No problem, it's a click away-- no need to book a meeting room, take all your gear (disrupting your workspace) and try to collaborate away from your desk in a mutual location.
Currently I sit beside people working that I previously worked on the same project with, but have now slightly diverged from. Trying to come up with a perfectly co-located office plan wouldn't work, because some number of people couldn't help but be misplaced. Not to mention we'd have to do it every few days!