Re: Hey Microsoft - here's an idea
"Want to know how it's free? I can download it right now from AOSP, build it, and run it, without cost. That's the definition of free."
No it's not. It's only costing you nothing because you're not planning to sell it.
Lots of licences allow no-cost use until you try to make money from the product, and this includes several open source products too: in fact, the GPL licence is deliberately compatible with this kind of business model. The original goal of the Open Source movement wasn't to give stuff away for nothing; it was to ensure that people who had often PAID for a product were also given the code, which would allow them to port it to a new hardware/OS platform in future. OSS was primarily about preventing vendor lock-in, not about forcing developers to work for nothing. See this: http://www.gnu.org/philosophy/selling.html
The various technologies under dispute on Andoid have a "no fee for non-commercial use" licence already, so you are fully entitled in law to pull the sources, build Android and use it. But, when you start to sell the product, you are no longer covered by this "non commercial" licence, and must obtain a commercial-use licence instead.