Shares of Rackspace Hosting (NYSE: RAX) plunged as much as 16% on Tuesday as investors panicked over a somewhat underwhelming earnings report. First-quarter earnings jumped 70% year over year on 31% higher sales, but analysts wanted another penny of bottom-line profits.

Is this a sell signal or a buy-in opportunity?

First off, I'd like you to feast your Foolish eyes on this chart:

RAX Earnings-per-share growth Chart

RAX Earnings-per-share growth data by YCharts.

Rackspace is riding the cloud computing trend like a champion rodeo artist. That chart doesn't include the latest figures, where sales growth dipped due to seasonal order patterns but earnings surged anyhow. On a trailing basis, both the top and bottom lines are accelerating.

And if you listen to Rackspace's management talking about the business, you'll come away thinking that the exciting part of this S-curve growth is just starting. "The shift toward cloud computing represents a massive multi-billion-dollar revenue opportunity that Rackspace has only just begun to tap," said CEO Lanham Napier in this week's earnings call.

More specifically, Rackspace's OpenStack cloud architecture is gaining support across the computing industry. Data giant IBM (NYSE: IBM) and Linux vendor Red Hat (NYSE: RHT) both joined the OpenStack consortium in April, lending heavy-hitting support on both the traditional and revolutionary sides of the fence. Rackspace drives that car and is sure to serve as the preferred provider of OpenStack cloud services.

The platform is in many ways a comparable alternative to Amazon.com's (Nasdaq: AMZN) Web Services products. Amazon is far and away the market leader today and is not letting up the pressure on the gas pedal, but Rackspace and OpenStack could give the e-tailer a serious run for the money.

Napier admits that Rackspace might see some short-term turbulence along the way, but the path to long-term profits is wide open. "The technology industry is in the midst of a tectonic architectural shift. Massive technology disruptions like this create once-in-a-lifetime opportunities for companies to seize the moment, take the initiative and lead the revolution," he said. "Our goal is to lead the revolution."

Skeptics would pin a "spin" sticker on that kind of big talk, but Rackspace walks the walk. So yeah, shares dropping back to January prices created a buy-in opportunity this week. You can quote me on that because I have a very profitable thumbs-up CAPScall riding on Rackspace. If I didn't, I'd start one today.

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Fool contributor Anders Bylund holds no position in any of the companies mentioned. Check out Anders' holdings and bio, or follow him on Twitter and Google+. The Motley Fool owns shares of Amazon.com and International Business Machines. Motley Fool newsletter services have recommended buying shares of Rackspace Hosting and Amazon.com. The Motley Fool has a disclosure policy.

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