Given AT&T's (NYSE:T) massive size, its recent $300 million purchase of USinternetworking looks fairly insignificant. However, the deal will give AT&T a leg up on the emerging megatrend of managed services.

Founded in 1998, USinternetworking gives corporate customers access to well-known enterprise applications from companies like Ariba (NASDAQ:ARBA), Microsoft (NASDAQ:MSFT), and Oracle (NASDAQ:ORCL). The company hosts the software on its own servers, and customers pay a fee to access those applications via the Internet.

The managed-services model is gaining considerable traction in corporate America. Its benefits include relatively lower costs (since a company only uses the services it needs, and can benefit from economies of scale); expert consulting; and no need to invest in servers, storage, or other expensive infrastructure.

That makes managed services a lot like a utility -- a business that AT&T amply understands. The company can leverage many of its current assets to build out managed services, including its massive customer base and its 30 data centers on four continents.

AT&T will have plenty of competitors, though. Key players in managed services include IBM (NYSE:IBM), Sun (NASDAQ:SUNW), and EDS (NYSE:EDS). Even is offering on-demand computing services. Will major customers trust AT&T to handle mission-critical information technology? Or might they rely on companies with much more experience in the space?

Even as AT&T enters the market, its competitors are getting stronger. IBM recently purchasedInternetSecurity Systems, considerably fortifying the security component of its managed services.

AT&T is wisely trying to position itself to catch a major trend, and it seems willing to make the necessary investments to succeed. But given the small size of the USinternetworking deal, I believe the acquisition will have little impact on AT&T's overall performance. Its merger with SBC will do far more to create shareholder value for AT&T. However, shareholders shouldn't expect immediate improvements in their holdings. If history is any indication, such massive mergers take several years to make a difference -- if they ever do.

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Fool contributor Tom Taulli does not own shares mentioned in this article.