Android developers can now get their hands on the "Cupcake" software development kit if they have the Android Dev Phone 1.

The updated firmware is available on the Android developers' Web site, and it adds a host of new features to the mobile operating system. One of the main complaints with the T-Mobile G1 is that text input could only be made with the physical keyboard, but that issue is addressed with a virtual keyboard in the 1.5 Android build.

The 1.5 version also will add stereo Bluetooth, video recording and playback capabilities, more home screen widgets, smoother page scrolling, faster GPS location information, and other improvements. Google said the 1.5 SDK is meant to be put on development handsets and not for personal devices that are used daily.

"If you have already released Android applications to the public, you should test the forward-compatibility of your application on the latest version as soon as possible," said the Android developer's blog. "It's unlikely that you'll encounter breakage in your applications, but in the interest of maintaining the best user experience, you should take no risks."

The search company hasn't given a definitive release date for Android 1.5, but the SDK release indicates it may be coming out soon. The HTC Magic is expected to be released in Europe this May, and it will require the 1.5 version of Android because it has no physical keyboard. Additionally, Samsung's first Android handset, the I7500, needs a software keyboard as well, and it's expected to be released in June. Existing G1 users will likely get the 1.5 firmware through an over-the-air update.

InformationWeek has published a 360-degree analysis of the first Android-based smartphone. Download the report here (registration required).