LinkedIn is where the headhunters, recruiters and HR people looking for professional hires actually are now. It’s a site where you post your curriculum vitae and connect with people you know professionally, as well as people you want to know professionally. If there’s any likelihood of your looking for another position anytime soon, it’s a very good idea to get yourself set up on there and to start building your professional network. Basic account is free.
Isn't that like telling the world you're looking for a job?
Might be OK if you're unemployed, but if I spot someone looking for a job, I might hire his replacement then let him go. Or at the very least, not waste raises and bonus money on him.