LinkedIn's new Lookup app connects you to your coworkers
The new iPhone app lets you search coworkers by name, title, skills, and more. When you click on a profile of one of your coworkers, you'll get his or her work details and experience (taken from LinkedIn, of course) and contact information (if it was added to Lookup). Even if the coworker's contact preferences aren't in Lookup, you could send a message from the app that will be delivered to their mobile phone.
This app obviously works best if you work for a large or medium-sized company, and don't work with just one group of people regularly. In that case, I could see how this app could be beneficial to the employees and the company as well (especially those companies that find it hard to update their intranets' information).
Here's LinkedIn's blog post introducing the app and the iTunes store link.