Get out your phone, and start following Jessica Simpson [1] — she joined the many celebrities on Instagram [2] yesterday and shared the exciting news on Twitter, writing, "It's official! I've just joined Instagram before it's not cool anymore!" Today, Jessica took to the social media site to reveal a sweet snap of herself with her daughter, Maxwell, and a "family moment" with her sister, Ashlee Simpson [3], and Ashlee's new fiancé, Evan Ross.