Today, Yahoo moved its open source cloud computing initiatives up a notch with the donation of its Traffic Server product to the Apache Software Foundation. Traffic Server is used in-house at Yahoo to manage its own trafic and it enables session management, authentication, configuration management, load balancing, and routing for entire cloud computing stacks.

Now comes a new rallying cry: software wants to be free. Or, as the tech insiders say, it wants to be “zero dollar.”

A growing number of consumers are paying just that — nothing. This is the Internet’s latest phase: people using freely distributed applications, from e-mail and word processing programs to spreadsheets, games and financial management tools. They run on distant, massive and shared data centers, and users of the services pay with their attention to ads, not cash.

While such services have been emerging for years, their rapid adoption has been an important but largely overlooked driver of the $44.6 billion hostile bid that Microsoft made to take over Yahoo this week.

When Yahoo acquired Zimbra in September 2007, some Zimbra backers worried Yahoo would mismanage the open source email asset. Fast forward to the present, and some Zimbra proponents have gone from concern to outright panic over Microsoft’s bid to acquire Yahoo (and, by attachment, Zimbra).