I've talked about how Star Trek-like communicator badges might help open new vistas of voice interaction with our mobile devices. I think they could easily allow any of us to record all our conversations for everyday lifelogging.
Lifeloggers wear computers to capture their entire lives, or most of them. It encompasses more than just recording conversations — it can not only include digitizing all of your documents, but counting your calories as well. Still, for purposes of this discussion, I'll stick with just audio.
The advent of smartphones with wireless connectivity, gigabytes of memory and long battery lives to me opens up the possibility of recording all of our conversations. If you're like me, you've said things you wished you could remember but couldn't, or wanted a recording of what others said as proof they said it. (And yes, I recall the Chappelle's Show skit on the "Home Stenographer.")
With a clip-on Bluetooth microphone in a badge that you could toggle on or off with a tap, I imagine you could start recording all your audio onto your smartphone, perhaps with a dedicated app. A large enough badge might carry a battery that can last a couple of hours, and might carry multiple mics to perhaps boost audio quality.
The audio quality might be poor for any number of reasons. You can't carry as much audio data over Bluetooth as you can over a nice audio cable. Mic quality can vary widely. You might experience wireless interference. You might not be pointing the mic the right way. Other people might be standing too far to record properly. (This is why radio reporters wear headphones during interviews — to monitor audio quality.) Still, it's a start. There's already a wireless camera that one can wear to record video onto one's smartphone, altho it currently has a cap of about 1 hour, so it doesn't record your entire life.
Digitally recorded conversations are of course quite easy to tag — at the very least, they'll come with date-time stamps. With speech recognition software such as Dragon, one might be able to get automatic (albeit likely imperfect) transcriptions as well, which could help you search through conversations for precise snippets.
The major hurdle could be legal, depending on jurisdiction. It's not always legal to record a conversation without the consent of all participants.