Instagram got a major update today in addition to faster uploads and autocomplete hashtags. The major update is that the photo sharing app now creates a photo album of images that you've liked. Previously, Instagram was just a stream of photos and liking a photo had no benefit to you, just an ego boost to the person who put it up. Now, aside from just the photos you've uploaded, you have instant access to view photos you've liked over and over again, unless, of course the owner takes it down.
Like pictures and they'll become a photo album
You can also add a little bit more to your profile by way of profile pictures (from your Photo Library) and web links. This way when you like someone's picture, they have somewhat of an idea who you are and who exactly is liking their pictures. So, now going from the simple take picture, add filter and upload app, Instagram is on its way to becoming a full on social network purely based on photography.