I feel that Linkedin is very professional. Linkedin is a business networking site cause of which they have to maintain few things. Facebook being social networking site, things can be taken little light on it. With Linkedin they are coming up with few new things so that the users can enjoy networking on Linkedin. Also I read somewhere about a site called MoDazzle which helps you access Linkedin on mobile through sms without internet. People can be a regular user cause of this MoDazzle. Check this: