Pamela, yes it still works. I first noticed it when I noticed artwork pages were redesigned. Titles are now at the top right.
Mark, you're right. There needs to be some text accompanying the previous/next buttons indicating that arrow keys can be used to advance through a gallery. It's common enough elsewhere, like Facebook, so many people might try it anyway..
Chuck, I don't see a flash.
Jessica, no, this is a new feature. Maybe you're thinking of something else?