When last we left Grey's Anatomy, George had horrifyingly told Izzie he loved her too, and Meredith and Derek got it on in the on-call room to punctuate their breakup.
The background for Meredith's opening VO is a beautiful shot of Seattle at night. "In the hospital, we see addiction every day." It's post-"I love you too" and George is exhilarated, babbling to Izzie about how amazing he feels, and how it's just like he's woken up. Mere's voice thankfully breaks in to the disgusting reverie to add, "It's shocking how many kinds of addiction exist. . . .