What do you want to do with GoogleDrive?
Currently the API is rather limited and you cannot use it as a cloud storage engine. The SDK is released just for Web Apps. You may use the REST API but still apps are granted permissions on file level.
The just released Google Drive sdk v2 supposedly now fully supports Android and is the preferred way to access Google storage rather than the Google Documents List API.
A B4A lib using this SDK would be VERY useful.