While developers have been hard at work building Android applications that can use GPS (Global Positioning System), Wi-Fi and cameras, they just discovered they likely won't be able to offer applications that use one common mobile phone feature: Bluetooth.

The most recent Android SDK (software development kit), released on Monday, says that Android 1.0 won't include a "comprehensive" Bluetooth API (application programming interface).

Developers aren't exactly sure what that means and a Google spokeswoman said the company plans to elaborate later on Friday in a blog post.

Some developers contributing to Google's Android forum say they find it hard to believe that Android 1.0, the first version of the Linux-based mobile operating system expected to become available soon, won't support Bluetooth. "HTC would not release a smartphone in this day and age that lacked Bluetooth support," wrote a developer going by the name Jeff Craig on the forum.

HTC's Dream phone is expected to be the first on the market to run Android software.

Google may plan to build support for Bluetooth into Android so that end users can wirelessly link standard Bluetooth gear, such as ear pieces, to the phone. But a lack of APIs would mean that developers couldn't build applications that use Bluetooth.

Some developers have focused on the word "comprehensive" to surmise that a future SDK update that Google has said might come in September could include very basic Bluetooth support.

End users and developers alike have eagerly anticipated the release of Android. Google's software along with Apple's iPhone software are rare new entrants into the mobile phone market.

While recent rumors suggested that Android would be released later than expected, Google has maintained that the first Android devices are on schedule to appear before the end of the year.