Currently I deploy using command line:
play war myappname -o myappname-war
APPENGINE_SDK_DIR/bin/appcfg update myappname-war/
I am developing in Eclipse. Can I deploy the Play! app using Eclipse plugin as I used to for standard GAE apps?
Right click on the project name in Project Explorer, you should see a 'Google' menu option, go on that and select Deploy to App Engine. You will have to add your app engine login info there.