I’ve never been much of a user of LinkedIn but I saw that they now offer an app called CardMunch that converts a picture of a business card into a contact you can use on your phone. The app is easy to use: you just open it, take a picture, and then wait for it to go to the server for processing. When it comes back you have a fully usable contact that can be converted to an iPhone contact and if the person has a LinkedIn profile it will let you connect with them.
I still am learning how to use LinkedIn for job hunting. I found that they have a job listings section but it seemed focused mainly on jobs in New York and there were not many legal job postings. The fun part is that you can see if people looked at your profile, although sometimes LinkedIn leaves an ambiguous description of the person who viewed you, presumably to sell a premium subscription where you can see their full name. Overall I think LinkedIn fills a nice niche for professional connections and the iPhone app adds a lot of value. If more legal employers in the area used it then I would probably use it more.