Sean Penn's latest romantic interest—or, as the Daily Mail puts it, his "latest younger woman"—appears to be singer Florence Welch of Florence and the Machine. They met at an LA charity event two weeks ago and sparks instantly flew, sources say. "Sean was flirting with her all evening," says one, and he's asked to see her again. Welch, who is exactly half Penn's age at 26, has been single since September. Now here's some Six-Degrees fun for you: She's good friends with Blake Lively, who married Ryan Reynolds, who used to be married to Scarlett Johansson, who was dating Penn last year.