General Motors unveiled a major, global social media campaign last week to mark the company’s 100th birthday. The platform, called GMnext, includes a commitment to allow/encourage its employees to participate in discussions about the company though blogs, wikis and discussion forums.

In a blog post about GMnext, Shel Holtz refers to the recent discussion about whether brands or organizations can actually participate in social networks — or only people representing those brands or organizations. GM, he notes, won’t try to participate as a brand, but will let its own flesh and blood employees represent the company. That obviously comes with risks, but it shows that General Motors understands that the communications landscape has changed radically over the past 18 months or so.

It’s particularly interesting to me that — for such an important anniversary — General Motors has decided to write its history through social media instead of commissioning an official biography. GM has set up an internal wiki through which employees and retirees will collaborate on an online company history.

This is all great.

But Dutch blogger Marco Derksen noticed that the company had failed to stake out its ground on various prominent social networks. So he went and secured GMnext branding on networks including Twitter, Facebook, MySpace, del.icio.us and Flickr.

He’s done it to prove a point and says he’ll gladly surrender the identities in exchange for a cup of coffee with GM execs in New York. The point is this: Just like it’s best practice to guard against cybersquatters by securing domain names similar to your own, it’s also a good idea to protect against twittersquatters (or MySpacesquatters or Facebooksquatters) by securing user IDs in those space.

I don’t disagree, but I think this raises an interesting issue. Most companies — even big ones like GM — don’t have the resources to participate in every social network. Best practice would say you pick the big ones (like Twitter, Facebook, MySpace) and join the conversations.

But, what if you don’t have the resources (or the commitment) to truly be part of that conversation? Yes, you could set up Twitter so it would update with blog posts, but what if there’s nobody available to really participate and discuss in this forum? Is it better to secure the Twitter ID so nobody else can use it, even if you aren’t really participating? Or is a disengaged presence even worse than no presence at all?