Developers and handset manufacturers can download the kit and begin to take advantage of the new functionality that Android 2.1 delivers.
The release on the Android Developers forum says "Android 2.1 is a minor platform release deployable to Android-powered handsets starting in January 2010".
Under the Platform Highlights section of the page it reads "Android 2.1 does not add significant user features, see the Android 2.0 Platform Highlights document for the latest user features".
That would all be fine and dandy if Google released the SDK to developers prior to launching Android 2.1, and it would seem more authentic if Google didn't just host a major press event last week to launch its Nexus One phone - the first device built on Android 2.1, where Google trumpeted and demonstrated an array of cool new features.
Apparently, either the Nexus One launch event was simply hyperbole and hot air and there is really nothing to be excited about with Android 2.1, or Google is trying to downplay the significance of the latest platform release to appease developers who are disgruntled that the SDK is being released after the launch of Android 2.1 and the Nexus One.
Imagine if Microsoft developed and released a new version of the Windows operating system, but didn't provide third-party vendors and developers with the tools to work with it until after it was released.
You don't have to stretch your imagination too far, because that was actually one of the biggest mistakes of the launch of Windows Vista.
Many vendors were simply caught unprepared for the Vista launch and users were left scrambling without compatible drivers and software to work with the new operating system.
That is essentially the same position that Google has put Android in.
While Google and HTC worked secretly on Android 2.1 for the launch of the Nexus One, Android app developers and handset manufacturers (other than HTC) were left to speculate and wait anxiously with the rest of us.
I attended the Nexus One launch event via the web, and in my opinion Android 2.1 was the highlight of the event.
The HTC Nexus One hardware is slick, but it was the unveiling of the new features and functionality of Android 2.1 that would make me want to go get one.
The living wallpaper feature seems like a battery-wasting novelty to me, but one that will most likely be popular with users.
Android 2.1 also extends the voice command functionality to allow users to speak into any text field.
With the Android 2.1 release, Google has also rolled out a revision to the USB driver that works with the Nexus One for syncing or transferring files between the phone and a Windows PC.
Those are just a few of the new features. They may be 'minor' tweaks to Android 2.0 from a coding perspective, but Google certainly went out of its way to spotlight and hype the new capabilities at the Nexus One launch.
Now that Google has unveiled the Android 2.1 SDK, developers can begin to validate their existing apps to make sure they are compatible with the latest iteration of the Android platform.
They can also begin to develop new apps that take advantage of features unique to Android 2.1.
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