Google planned to announce on Tuesday that the source code for its mobile operating system, Android, is now available for anyone to use free.
The move was expected, although the timing was uncertain.
Developers can find the source code on the Web site for the Android Open Source Project.
"An open-sourced mobile platform, that's constantly being improved upon by the community and is available for everyone to use, speeds innovation, is an engine of economic opportunity and provides a better mobile experience for users," said Andy Rubin, senior director of mobile platforms for Google, in a statement.
The first Android phone isn't yet on the market -- the G1 goes on sale in the U.S. from T-Mobile on Wednesday. Journalists were first able to publish reviews of the G1 last week.
Google expects that by making the source code for the operating system open, a wide variety of applications will appear, as will cheaper and faster phones.
But Google's model for Android has some critics. The LiMo Foundation, which publishes specifications for middleware for mobile Linux devices, and of which Google is not a member, says that Google's model might be too open.
"There's a debate about whether Google's approach to openness is sustainable and good for the industry," said Andrew Shikiar, director of global marketing for the LiMo Foundation.
Android will be released under the Apache license, which doesn't require developers to share their changes to the code back with the community, he said. This is one of the reasons why some people wonder whether Android will become fragmented as various incompatible versions of the software appear in phones across the market.
In the FAQ section of the site for the Open Handset Alliance, the group supporting Android, Google says that using the Apache license will let manufacturers innovate on the platform and allow them to keep those innovations proprietary as a way to differentiate their offerings.
Shikiar floats a more sinister reason that he's heard for why Google may have chosen the Apache license. "If it's fragmented and scattered, and the only common version is the Google-optimized one, it's good for them," he said. That's because the G1, which is optimized by Google, comes loaded with many Google services that can eventually bring in revenue for the search giant. If that turns out to be the best version of an Android phone, more people will use it and so, presumably, more people will be using Google apps.
LiMo and Symbian, which also is going open source, each use different licenses, but both include obligations for people who change their code to share their changes, Shikiar said.
Shikiar also criticized Google because he said the search giant hasn't created any sort of governance model for the Open Handset Alliance and doesn't publicly publish the group's membership agreement. A governance model spells out for participating companies exactly how their intellectual property can be used by other members. Without it, members might be reluctant to contribute, he said.
The OHA did not reply to questions recently posed regarding its choice of license and its governance model. Google also was not immediately able to respond to similar questions.