Not even social media is safe from the rumblings of a wounded economy. Social networking powerhouse LinkedIn, the premiere professional networking site, has decided to preemptively layoff 10% of its workforce.

The company does not seem to be in financial trouble; in fact it just pulled in $22.7 million in financing a few weeks ago, but companies around the world are tightening their belts whether they’re losing money or not.

LinkedIn might be trimming unnecessary workers after a successful rollout of their new Application Directory.

Much like Facebook applications, the on-site apps are installed in your profile with a few clicks and do not reside on your hard drive. Unlike Facebook, LinkedIn will be extremely tight-fisted about allowing apps on their site. Instead of letting just anybody write one, LinkedIn requires you to type up a business case for your app and provide a “clear business utility to LinkedIn users. LinkedIn is not a place for sheep throwing.” These guys aren’t messing around.

With the economic downturn, a commitment to keeping out just-for-fun applications and a maturing (OpenSocial-based) development platform, it looks like social networking is finally going to have to grow up.