I upgraded my Cordova onto the latest v3.6.4 using below command:
npm update -g cordova
Then created a new project and when trying to add Android it shows below message. However it adds other platforms like Blackberry10.
npm http GET https://registry.npmjs.org/cordova-android/3.6.4
npm http 404 https://registry.npmjs.org/cordova-android/3.6.4
Unable to fetch platform android: Error: version not found: 3.6.4 : cordova-android/3.6.4
use
npm update -g cordova@latest
this installs the correct release versions, 3.6.3, not the 3.7.0 rc which produces this error