Seattle-based Amazon has also been making more serious use of Twitter.

Under a program announced this month, Amazon is giving its legion of affiliates—who direct traffic to Amazon through links and banner ads—a way to make money doing the same thing on Twitter. Affiliates collect referral fees if someone clicks on a link or ad and ends up buying something from Amazon. Now they can tweet about a product for sale on Amazon, and if the tweet results in a sale, they’ll get a fee.

“There’s a substantial amount of traffic that’s being generated off Twitter for Amazon,” said Brian Walker, a Seattle-based e-commerce analyst for Forrester Research, a technology research firm. “Now they’re adding to the ability to capitalize on that and promote it as an affiliate.”

The new program represents an evolution of Amazon’s relationship with Twitter. Jeff Bezos, Amazon’s founder and CEO, was an early-stage investor in the microblogging site, and Amazon has used Twitter to send out deal alerts and draw attention to new services. Now Amazon is seeing possibilities in Twitter as a sales-referral engine.

In the case of Microsoft, although the company gives up a measure of control—and potentially profits—by not operating a direct Twitter or Facebook rival of its own, it also can leverage the momentum and credibility of those services by working with them rather than against them.

“I think they’ve looked at their online business pretty carefully and realized that there was no value in going after every single thing that a competitor had,” said Matt Rosoff, analyst at the Kirkland-based Directions on Microsoft research firm.

Instead, he said, the company is putting most of its focus on making its Bing search engine a credible rival to Google. That effort includes Microsoft’s pending search-advertising partnership with Yahoo, its longtime rival.

Still, tech companies’ new interest in the big social networks has increased speculation that the social networks could be “meaningful acquisition targets,” said Walker of Forrester Research.

He noted, however, that such sites have proven difficult to monetize and that the “jury is still out” on their business model.