How Exactly Does Gmail's New Phishing Technique Work?

I've seen this around the news for a while: Hackers exploit new phishing technique to get login credentials of users.

According to the news, the main difference is that the address bar shows the url of the real site so even the tech savvy are getting hoodwinked.

In the above picture, the url of the real Gmail login page can be seen.

My question: How exactly does this phishing scam work?