However, for all the others already situated with Android 2.2, you can expect to see some improvements with Gmail on your handset. For starters, the message actions bar will continue to stay on the top of the screen as you scroll through a long email – so you'll always have it on hand for lengthy messages. Secondly, you'll be able to view threaded emails more easily, like on a desktop, by simply clicking on “Show quoted text” to see the contents of a previous message. Lastly, there is now limited support for Priority inbox which is classified with the “Important” label.
source: Google Mobile Blog