It could, if you used it to hit your boss, or a co-worker. Or if you used it to smash your office desk to bits.
My point is, the hammer is just a tool. It’s how you use it that could get you fired (or not). It’s the same for these social networking tools, such as Facebook and Twitter. There’s lots of press lately about how using these tools could ruin your reputation, or get you fired. The latest example being this article on MediaPost.
And yes, what they write is completely valid. Companies are still not fully adjusted to this new world of social media, and if you overstep the bounds that they set, you could get fired. So yes, you probably do have to be careful, to a certain extent.
At the end of the day, though, it’s not about the tool. Twitter, Facebook – these are just tools. How you use it could get you fired, true. But that’s the same of any tool.