3. Anyone who blogs or twitters or talks to anyone about their life, currently
"I wish I had thought to take a picture/video of that event."
"I wish I could remember that person's name that I met last week."
This is another incremental step toward a searchable, verifiable, rewindable stream of your life, and the benefits are enormous. A lot of people I know, including myself, use search all day every day. I probably use Google a hundred times a day or more, for the most trivial questions, or just to see if there's a quick known answer to some problem I'm thinking about. I am really, really looking forward to being able to do something similar with my real life.
I've organized my life around simplicity of schedule, so I think this will be even more useful for people who are constantly on the go and trying to remember what they need to do next and who they're doing it with and for. The stuff that various email apps do now with recognizing appointment language and offering to add things to your calendar, for example, seems a natural for applying to realtime life.