Official Gmail Blog: New in Labs: Inbox preview
Whenever I open up my inbox at work, I'm never surprised to find several new messages waiting to be read. The same thing can't always be said about my personal Gmail account. Sometimes I end up checking my mail only to find nothing new there.
No big deal, really. But now imagine that you access Gmail on a super slow connection from a remote place in Ethopia where it might take minutes to completely load your inbox. The disappointment is larger when you find out that there is nothing new to read and you could have saved all that time.
To ease this pain a bit, we created a new feature in Gmail Labs called Inbox Preview. While Gmail is loading, a simple, static preview of your inbox with your ten most recent messages is displayed. Turn it on from the Labs tab under Settings, and if you're on a slow connection you'll know from the start if it's worth the wait.
Official Gmail Blog: New in Labs: Inbox preview
Another cool feature from Google team.. I think they should now plan to come out of beta phase