Can companies be part of the social world?

There is some debate going on at the moment about whether companies are able to engage in social media. The crux of the issue is whether a company, in essence a body made up of a number of individuals can communicate as a single entity.

One opinion says that humans connect to humans and its not the domain of brands:
Shel Israel makes this point clearly here:
http://redcouch.typepad.com/weblog/2007/12/can-brands-be-s.html

However the alternative view is that companies need to be able to exist in the social media space and engage in dialogue and interactions with their customers/users/influencers
Forrester have been advocating this approach for almost a year now and their 'Groundswell' book and their article that covers 5 main reasons for companies to get involved:
Listening
Speaking
Energizing
Supporting
Embracing

Their more recent blog posting about this subject goes into more depths.

Where are you on the Purist - Corporatist scale?