I'll go with the end of the ban on women in combat. As with the demise of DADT, this is one that isn't ever going to be reversed, and will make a big difference for the people involved.
For didn't matter...the whole Hillary goes to the Hill thing is too obvious, right? (Not that I'm against oversight hearings). If you don't like that, I will say that Inaugural Addresses are invariably overhyped.
So that's what I have. What did you notice? What am I missing? What do you think mattered this week?