It's the oldest trick in the book. Have dress, add jacket, it's for work! Ditch jacket, it's for happy hour! I know the mags have been suggesting this for years, but I always love to see a day-to-night situation in action.
I wore this dress and jacket to work, and then tossed the jacket to show off the sheer cut-outs for dinner with friends. The purse swap was a quick fix too, since I just tossed it in my larger bag. There's no rocket science here. It's just planning your outfit for the whole day, instead of just your first event.