The legendary Peter Lynch advised investors to research companies that are expanding their facilities -- one indication that the business is growing and prospering. With this in mind, a recent real estate transaction could offer clues about the outlook for two tech titans.

Silicon Valley legend Hewlett-Packard (NYSE: HPQ) has announced the sale of its 98-acre Cupertino, Calif., campus to Apple (Nasdaq: AAPL). The purchase should roughly double the size of Apple's Cupertino facilities.

Can you say "growth plans?"

Mobile computing has been core to Apple's recent success, and it's a key growth opportunity for tech companies in general. It has also been a focus area at HP for years.

This real estate transaction doesn't offer much insight regarding HP's earnings prospects. For years, that company has been more about cost-cutting -- including real estate consolidation --than revenue growth. The deal is likely just part of the plan, and embedded in expectations.

HP intends to upgrade its Palo Alto headquarters and move in several thousand Cupertino employees. An internal email reportedly stated that both its Cupertino and Palo Alto campuses are about 60% utilized.  (What's worse for morale: Working in a quasi-ghost town, or being forced into a longer commute in heavy traffic?)

Meanwhile, in shinier territory…
Despite Apple's $65 billion in sales, the company's stock has defied the law of large numbers to continue growing. Will the launch of a Verizon (NYSE: VZ) iPhone help Apple to continue to take market share from Research In Motion's (Nasdaq: RIMM) Blackberry, and stem phenomenal market share gains by phones using Google's Android operating system? Will the Mac continue taking market share from Dell (Nasdaq: DELL) and Acer PCs? How much can offering the iPad in more international markets help?

Purchasing HP's Cupertino campus suggests that Apple anticipates boffo growth for years, a positive for shareholders. For starters, Apple doesn't take full possession until 2012. The HP campus accommodates an estimated 6,500 or so workers.

If Apple maintains its recent trajectory, it might outgrow the HP facility before 2012. In its fiscal year ended last September, Apple added 12,300 full-time employees, a 36% increase. Don't be surprised if Apple tears down HP's decades old low-rise office buildings and replaces them with mid-rise buildings that can house more workers. Turning HP's Cupertino campus into a teardown would be an even larger symbol of shifting fortunes in the tech industry.

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Fool contributor Cindy Johnson owns both Apple and Hewlett-Packard products ... but more of the Apple ones. She does not currently own shares in any of the companies in this story. Google is a Motley Fool Inside Value recommendation. Google is a Motley Fool Rule Breakers selection. Apple is a Motley Fool Stock Advisor pick. The Fool owns shares of Apple and Google. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.