I wasn't sure if this was a new feature I was seeing or a quirk in my browser/session. I was answering a question on SO and decided not to finish it (I realized I didn't know as much about the subject as I thought my answer out). To clear the answer I reloaded the page... but my answer was still there. I was curious, so I deleted the text, re-loaded the page, and it was still there! I even went so far as to close the tab (in Chrome, so the process exited), and then load it in a new tab, and the answer was still there!
At the time I thought it was a new feature - some sort of utilization of HTML5 localStorage to save someones answer in case of a browser crash or somesuch (and given how lengthy some answers can be, this seemed useful).
However, out of curiosity I just tried to duplicate this behavior again today (saw this behavior a day or two back), but was unable to do so. Wasn't sure if I wasn't triggering the conditions correctly, or if what I was seeing the other day was just erroneous.