While nearly all of the analysis of Microsoft's offer to acquire Yahoo! for close to $45 billion has centered on the Redmond giant's intent to compete with Google for online advertising dollars, swallowing Yahoo! would also plant Microsoft squarely in the middle of the open source software arena. Yahoo! is so firmly entrenched in open source software-from the server farms that its own site runs on, to its Zimbra division delivering open source apps, to the APIs that it offers to application developers-that Microsoft, as corporate parent, would have no choice but to shed much of its long-standing antipathy toward open source.