After a phone freeze and reboot around midnight this evening, I am now seeing a sync of read/unread as well as sent items between the GMail web UI and my device messages folder.
Give it a try; send an e-mail from the GMail UI, and you will see it show in your Messages folder (provided you show sent) after a few minutes.
Delete from the GMail UI to the device is still not working for most of us, so it looks like we are getting closer to full 2 way GMail sync.
