After 219 developers signed a petition asking for more information about Android's progress, Google offered a two-sentence reply saying thanks.

Developers building applications on Android, Google's mobile phone software that is still in the making, have been venting their frustration at what they say is a slow pace of updates released for the SDK (software development kit) and a general lack of information about the development schedule for the software.

In late June, developer Nicolas Gramlich, a computer science student in Germany, started a petition asking Google to release more updates to the SDK and to offer developers information about the development timeline of the SDK. Last week, he sent the petition to the Android Advocate at Google. The petition has by now been signed by 245 people.

A couple of days later, Gramlich received a response from Google via e-mail and he posted it in the company's official Android discussion group. The response has underwhelmed the developers.

"We appreciate the enthusiasm of our developers and we're excited that you're so passionate about the Android platform. Thanks for taking the time to send this," reads the note from Google signed by someone identified simply as David.

"Sounds like a polite way of saying nothing: a verbal silence," wrote a developer identified as Shane Isbell, on the Android forum.

Google has not replied to a request for comment or to confirm that the note came from the company.

In addition to the perceived slow release of SDK improvements, developers were also recently frustrated after a Google employee accidentally posted a note on a forum indicating that the company is offering an improved SDK to a small group of developers who won a contest. Some of the other developers were dismayed to learn that they are working on an inferior version of the SDK.

Now, developers are wondering why the continued silence from Google even after the petition. Perhaps there is some component of the SDK that Google doesn't want its competitors to see until Android launches, another developer identified as Denis Beurive speculated on the forum.

Or, perhaps the SDK isn't particularly stable and so Google doesn't want to release another weak version of it, he wondered.

The unrest comes amid speculation that the final Android software is delayed and after Apple has sold millions of iPhones to people who can buy applications from developers for the phones. Google has said that it is on schedule to launch Android and that Android phones will begin to appear this year.