Androidの各バージョンのNewFeature
http://developer.android.com/intl/ja/sdk/android-1.5-highlights.html
http://developer.android.com/intl/ja/sdk/android-1.6-highlights.html
http://developer.android.com/intl/ja/sdk/android-2.0-highlights.html
http://developer.android.com/intl/ja/sdk/android-2.2-highlights.html
http://developer.android.com/intl/ja/sdk/android-2.3-highlights.html