It might not seem important that Evangeline Lilly got a haircut, but The Wasp is arguably more important in The Avengers universe than her main squeeze, Ant-Man. She's been there since the beginning and stuck around longer than Pym or Lang.
We still don't know if Lilly's character, Hope van Dyne will don the titular wings, but this haircut is one step closer.
Big Ant-Man news (and maybe some spoilers) is coming from Hall H and the Marvel Studios panel. Former Lost star, Evangeline Lilly finally has a role to announce, she's playing Hope van Dyne, Hank Pym's daughter. Hank Pym (Michael Douglas) is the man who invented the shrinking technology, aka Pym Particles, and now he's taken Paul Rudd's character, Scott Lang, under his wing to eventually take over the business.
But Rudd isn't his first mentee. They also announced that House of Cards star, Corey Stoll is playing Pym's business partner, Darren Cross who is using the company for nefarious purposes. It also sounds like he'll be using the Pym Particles to transform himself into Yellowjacket, the big villain of the movie.
It's a good thing I liked Iron Man 1, since apparently they're just recycling the plot.