Google Labs recent tweak allowing Google Voice users to play back their messages directly within Gmail. Prior to the add, Google Voicers clicked on play message, which would then pop open a new page in their browser a less-than-streamlined way to retrieve messages.
To activate the Google Voice feature, go to the Labs link in Gmail, scroll down to the Google Voice player in mail feature and select and save to enable. Google also writes that messages played from Gmail will appear as read in your Google Voice in-box and won’t be played again when you check new messages via your phone.
It is the small tweaks that make the difference