There is a movement coming over from America called ROWE (Results Only Work Environment). There's plenty of good stuff to it, however its basic premise is that 'face time' for face time's sake is pointless. I understand the sentiment, but actually I don't agree.
How many times have you been at work and met someone in the corridor, jogging your memory and reminding you that you needed to ask them something. As the conversation continues you both realise you're missing an important bit of information and together you walk to the department who can help you.
Or else at lunch you sit down next to someone you don't normally talk to. You start to swap stories about the hellish morning you've had and the beginnings of a new working relationship are forged.
Maybe you're struggling with a new client. A friend tells you that actually Mike, the new business guy, has worked with your client before. As it happens Mike has some time right away, so that you go and have a coffee together and you've got the inside track on how to deal with your client within the hour.
There are lots of great reasons to work from home - sometimes you end up working much more efficiently. Emails, webinars and conference calls mean there is a technological solution to pretty much every communication need you can think of. However there is a serendipitous element to life in an office (a good one) that one loses when one doesn't have 'face time'. As Mike the new business guy might say, 'you have to be in it, to win it'.