QwertyWEB

Since after Gmail becoming full functional and removing BETA tag , loads of new features have been built up for highest level of security .
And what more , protect spam and hoax emails believed to be send from false alike servers , Gmail has now launched a new lab feature , The “Authentication icon for verified senders” one .
The "Super-trustworthy" new feature have 3 main cool new rocking features :

1. The sender, usually a financial institution, is a target of phishers,
2. All of the sender's email is authenticated with DKIM,
3. Gmail rejects any fake messages that claim to come from this sender, but actually don't.

To enable this feature go to Settings and then labs or click this link

You have to click on enable

Here's a look on post on their official Gmail blog

We're always looking for new ways to protect Gmail inboxes from spam and phishing. Last year, we started taking extra steps to protect you from fake eBay and PayPal emails, requiring that any email claiming to come from one of eBay's or PayPal's domains actually comes from them. We do that by looking at the "From" header, and when it says "ebay.com" for example, it means it really did come from ebay.com. Anything else is rejected; it won't even appear in your spam folder because Gmail won't accept it.

Link : http://gmailblog.blogspot.com/2009/07/new-in-labs-super-trustworthy-anti.html

Right now this feature only checks on ebay and paypal ,but more will be coming soon