Social media moves so fast, it's hard to keep up. Here are the week's top stories in scan-friendly format:

  • Almost Half of Americans Use Facebook, Only 7% Use Twitter
  • Facebook Now Powers TechCrunch Comments
  • LinkedIn Unveils Company Search: Showing Whom You Know at Companies
  • Social Media Gives Your Doctor Anxiety

Almost Half of Americans Use Facebook, Only 7% Use Twitter

In the online world, where we eat and breathe social networking, we often take for granted that our craft has gone mainstream. It seems everyone these days is online, using services such as LinkedIn, Facebook and Twitter, right? Facebook alone has 600 million users, so everyone must be on it, right? eMarketer, an online research firm, recently conducted a study to gauge how mainstream social media use is among adult Americans.

For Facebook, 42.3% of Americans use the service at least once per month. Meanwhile, only 7% of Americans use Twitter and only 9% of Americans who are already Internet users use it. Facebook has made inroads with its use of popular services such as photos, messages and groups. These services resonate with mainstream Americans, whereas Twitter is used mainly by more hardcore Internet users.

Twitter has shown some decent growth in the last few quarters, but the service has largely remained the same, and the company has chosen not to add new features to enhance the service. Facebook, on the other hand, is constantly revealing new features, making it more attractive to online users and fueling its colossal growth pattern.

Facebook Now Powers TechCrunch Comments

Facebook is looking to be the go-to resource for conversations and interactions online. In a move toward this goal, Facebook rolled out the ability to power commenting systems on websites and blogs. To this end, TechCrunch has adopted Facebook for all comments on its website, meaning commenters must have either a Facebook or Yahoo account to leave a comment on a TechCrunch blog post.

Facebook's new commenting plugin shows how the company wants Facebook to be your online identity and main conversation engine. For users, it makes your comments left on blogs and other website visible on your Facebook stream so your colleagues and friends can see your activity across the web.

Some TechCrunch readers are upset at the move and do not want to be forced to leave their Facebook identity whenever they leave a comment on a TechCrunch article. GigaOm has employed Facebook's system but also makes it possible to login with WordPress logins. Would you use a Facebook or third-party login system when leaving a comment?

LinkedIn Unveils Company Search: Showing Whom You Know at Companies

Let's say you're looking to get a position in a company you really admire. These days, it's often the case that whom you know is more important than what you know. If you're looking at being employed at a certain company, it might help to have a friend or former colleague get a foot in the door. This is where Company Search comes from, which is a new feature recently rolled out by LinkedIn.

The feature lets you search for companies and see whom in your network is now employed at said company. With the follow feature, you can keep up-to-date with news, hiring and other events the company puts out on its company page. This search will be good for job seekers or anyone looking for insight into a company through their own social network.

Would you use Company Search on LinkedIn? Aside from knowing where a Facebook friend is, this Company Search seems to fill a need. Also, it allows you to track former colleagues whom you may have lost touch with and see if they work in a particular department.

Social Media Gives Your Doctor Anxiety

Social media is magical because of the connections it spawns. By barely lifting a finger, anyone can reach out and get opinions on all kinds of subjects. This is one of the reasons social media makes doctors cringe. A recent CNET article gives some insights to the underlying issues. In short, because of privacy issues, partial problem descriptions and search engine optimization make the web a good place to get general information, but not a detailed diagnosis.

For example, In a recent Quora question, someone with a fractured ankle asked how to train for a marathon despite the injury. Luckily, a person answering the question urged the questioner to seek medical advice. The web is full of bad medical advice that is sometimes easily discovered. Also, because of health care laws, doctors are advised not to give advice, even if they feel compelled.

The American Medical Association has told doctors that social media is beneficial, but warned about weighing in on online conversations because of a doctors' desire to preserve their reputation and privacy. Health care is a relationship that is best left to the provider's office, not in any public online forum. While general information can be sought online, personal diagnoses should be sought in close conversation with your medical provider.