By Tom Taulli

A few years ago, eBay (EBAY) seemed like a washed-up Internet operator, just an online secondhand store amid a growing field of true online retailers.

The company's recently reported third-quarter earnings are just another reaffirmation that CEO John J. Donahoe has changed all that. He has his company back to attacking growth through mega-markets, specifically mobile.

In Q3, eBay's revenue increased by 15% to $3.4 billion and earnings came to 55 cents a share, a penny above Wall Street expectations. The company also gave a rosier outlook for the full year: EBay expects revenue of $13.95 billion to $14.1 billion and earnings per share of $2.32 to $2.35, both improved from forecasts in late August.

The conference call was rife with talk about mobile -- especially concerning how important eBay's PayPal service has become. PayPal now has more than 117 million active accounts across the globe, and the company is forecasting that its mobile revenue will reach more than $10 billion in 2012.

No doubt, a significant chunk of this will come during the Christmas season, as shoppers are likely to use their iPhones, Galaxys and other smartphones to do their shopping. However, a key part of the PayPal growth strategy is to move aggressively offline. 

Consider that it is integrated across retailers like Home Depot (HD), Guitar Center and Abercrombie & Fitch (ANF). Plus, PayPal also recently announced plans to team up with Discover Financial Services (DFS), which will put PayPal in touch with more than 7 million merchants by next year.

Not that PayPal is the only story. Ebay also has created compelling mobile apps, which saw more than 100 million downloads in the quarter, and were used by sellers to post roughly 2 million items per week.

It's inevitable that the smartphone will become the wallet of the future, considering it's ideal not just for purchases but for doing research on the products you're about to buy. And through its numerous deals with PayPal, eBay certainly is poised to be a huge beneficiary of this e-commerce trend.

EBay shares are up more than 60% this year. But despite that fantastic run, eBay still fetches a reasonable valuation. It currently trades at a price-to-earnings ratio of only 17 -- not cheap but certainly still compelling in light of eBay's full-year revenue growth rate of roughly 20%.

Bottom line: If you're an investor looking for a solid play on mobile, you can find it on eBay.

Tom Taulli runs the InvestorPlace blog IPOPlaybook, a site dedicated to the hottest news and rumors about initial public offerings. He is also the author of "How to Create the Next Facebook." Follow him on Twitter at @ttaulli. As of this writing, he did not hold a position in any of the aforementioned securities.

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