The Android platform is a software stack for mobile devices including an operating system, middleware and key applications. Developers can create applications for the platform using the Android SDK. Applications are written using the Java programming language and run on Dalvik, a custom virtual machine designed for embedded use, which runs on top of a Linux kernel.
There is a SDK at Andriod Website the two features that interest me is how application is created equal so you can create your own dialer for example and replace the existing one, as well as the multitasking nature of the platform.