Groupon has released its numbers ahead of its first ever quarterly earnings call and as expected, they’re not terrible. The company earned had revenue of $506.5 million, a 194% increase over last year. Doubling its revenue is impressive but it shows slowing growth–this quarter last year Groupon had grown revenue by 400%. A chief concern of analysts and investors is whether Groupon can continue its lightspeed growth for long enough to justify its lofty valuation.

Perhaps most important this quarter is Groupon’s jump in operating income. A chief complaint of the company has been its insane customer acquisition costs, which have eaten into its profits. But Groupon remains unprofitable. The company earned $15 million in operating income this quarter, compared with an operating loss of $336.1 million this quarter last year. Much like its unprofitable competitor LivingSocial, Groupon has spent the last several years investing, expanding and acquiring (including this weeks’ acquisition of Adku). Now, the hope is, is time to harvest those investments. The company trades at a rich 42 times 2012 Ebitda, according to Citi analyst Mark Mahaney. Plenty would call that overvalued given the multitude of risks the company faces (barriers to entry, faddishness of its product, to name a few); Mason’s job on the call will be to justify his company’s $15.68 billion market cap.

Since last quarter was the fourth, Groupon also reported year-end numbers: The company earned $1.6 billion, a 419% increase over 2010. The company expects to earn $510 million next quarter, with income ranging form $15 million (flat) to $35 million. We’ll be on the conference call listening for nastigrams from the analysts.

Update: Yep, I read the release wrong. The company had operating income of $15 million compared with an overall operating loss of $336 million last year, but posted an unexpected loss of $42.7 million.

Update 2: On the call, analysts repeatedly asked Mason about what he expects in the year ahead for Groupon’s new products, including Groupon Now, Getaways and Rewards. He declined to give guidance on how the new products might contribute to Groupon’s bottom line because they are less than six months old. However, Mason touted Groupon’s progress in shrinking customer acquisition costs, a priority for the company since last fall. They fell by 22% last quarter after reaching over 100% at one point last year. Mason said they would never shrink to the 5% or 10% level of companies like Amazon and Netflix, but thanks to more targeted marketing strategies that focus on leading prospects to a deal rather than a sign up form, progress has been made. “Every quarter there is a smaller pool of subscribers to go after because of the larger penetration we’re going to hit in some of our more mature markets,” he said.