While full nudity isn't allowed on Instagram, for example, you can still get away with posting pretty racy images. If those images have been reported and Instagram's team deems them "sensitive," they'll be blocked by default. You can simply tap the screen to get the full image, though. It's not a bad addition, but Instagram should probably offer a way to turn the setting off for people who don't really care about having images filtered.
Another change announced today is one everyone should take advantage of: two-factor authentication. It's been around in limited fashion for a while, but now it's available to everyone. It works just like you'd expect -- once turned on, you'll need a code sent to your phone via text message every time you log in. Before you turn it on, just make sure that the phone number linked to your Instagram account is the current number you're using.
Instagram has also launched a stand-alone website as a one-stop shop for keeping your experience on the service safe and positive. It'll give you an overview of things like blocking accounts, tagging photos, managing comments and other things you'll use to control your experience. All these features should be rolling out today, so check the Instagram app and site if you want to try this all out.