I disagree with B.L.'s take on Chris's take that the internet is anti-corporate.
Paltry click-through rates, pop up and ad blockers, snarky comments and "no marketers/PR folks allowed" Second Life islands tell me otherwise.
Before I go on, I want to qualify what Chris was inferring -- most people don't want companies intruding in their personal space online, which is not the same as "not at all", and certainly differs when it's "done right".
Now -- do I think brands deserve representation online? Absolutely. If my clients are being misrepresented or their consumers want to engage then they should absolutely have that discussion.
However, it is important to remember why people are going online. Looking back, the internet wasn't created for marketers - it was created to share information. BBSing in the 80's and rudimentary 90's web sites weren't about being marketed to - they were about sharing information. Have web companies been able to sustain and become successful? Absolutely. And the chances are they're providing a service that makes life easier, like online banking or access to products not available where they live or social networking with friends.
Non-internet companies saw the opportunity to reach these audiences and potentially make money in this space, plain and simple. They're trying to figure out how to engage properly, which is where we come in.
People go online, do their business and leave. That explains why the majority of people (present company excluded) visit the same handful of sites and move on with their lives.
I think the brands B.L. mentioned have been able to connect online (you left out GM!) because they respect the rules of the venue and are not intruding in others personal space.