Facebook automatically creates alt tags for images and describes them with text such as "three people outdoors with a tree." As someone who's blind I found it interesting for five minutes and have not visited Facebook again. I have been totally blind since birth, and I don't think any amount of textual description will make me interested in scrolling through a photo stream. I could see this being different if you lost your sight later in life. OCR in it's current state is a bad idea as a primary way to get information when using a computer. My screen reader allows me to use OCR to find out what's on the screen. It works OK for specific situations such as an inaccessible installer with a couple controls. It falls down if I were to try and use OCR to read Java code.