The party line on LinkedIn's competition with Facebook is that the two sites serve different markets, and LinkedIn has nothing to worry about from the rise of Facebook's popularity among Silicon Valley professionals. LinkedIn's professional focus makes it a favorite of recruiters. Except, that is, for LinkedIn's recruiters, who have been placing job ads, like the one above, for engineers on Facebook. LinkedIn's HR department, meet LinkedIn's PR department. You might want to have some words with each other.