LinkedIn just reported a 101 percent increase in revenue for the first quarter of 2012, as compared with the same time period in 2011. Its Hiring Solution products accounted for 51 percent of that revenue, with a YOY upswing in job-product dollars of 121 percent. Additionally, those members who opted to buy Premium rather than free profiles increased 91 percent. The economy, and the increasing importance in social networking for job hunting and recruiting might well account for the latter upsell upswing.

“LinkedIn grew over 100 percent for the seventh consecutive quarter and achieved records for adjusted EBITDA, operating and free cash flow,” said Steve Sordello, CFO of LinkedIn, in the company earnings announcement.  “We remain focused on investing in our technology and product platform as well as expanding our business in new international markets and customer segments.”

Despite the good news, however, other social recruitment platforms just might be nipping at LinkedIn’s candidate-traffic heels. Facebook-focused BranchOut just celebrated its own upswell in audience, and secured $25 million to keep the competition at bay. For more on this story, see our upcoming CIR.

Here’s the LinkedIn earnings release.