David Gelertner was writing about the concept of Lifestreams back in 1995 and 1996 and predicted the modern internet in the book Mirror Worlds in 1991.
A lifestream is a time-ordered stream of documents that functions as a diary of your electronic life; every document you create and every document other people send you is stored in your lifestream. The tail of your stream contains documents from the past (starting with your electronic birth certificate). Moving away from the tail and toward the present, your stream contains more recent documents — papers in progress or new electronic mail; other documents (pictures, correspondence, bills, movies, voice mail, software) are stored in between. Moving beyond the present and into the future, the stream contains documents you will need: reminders, calendar items, to-do lists.
You manage your lifestream through a small number of powerful operators that allow you to transparently store information, organize information on demand, filter and monitor incoming information, create reminders and calendar items in an integrated fashion, and “compress” large numbers of documents into overviews or executive summaries
There are now several ways to realize the vision of lifestreams today. There is twitter with geotagging and there are social media aggregation sites like posterous.
When I asked Gelertner how different twitter with geotagging and RSS feeds (with RSS readers) are from his vision of Lifestreams, he answered that twitter has the realtime aspect but is too much about trivial things. I believe that more depth and relevance is a matter of better filtering and searching of twitter and subscribing to people and things that have a higher ratio of indepth twittering. Twittering is able to circumvent the short message format including links to details articles. RSS readers lets you merge the output of many websites that you choose to follow.
The Lifestreams vision would want better searching and filtering for relevance, authority, time ordering and location and have better more powerful manipulation. Currently it is usually difficult to efficiently and effectively subscribe to part of a twitter or RSS feed.
Mirror Worlds is a book written by Gelertner in 1991 (the link is to the Google Books copy). In Mirror Worlds, Gelertner predicted and envisioned much of what exists in the modern internet and lay the foundation for the Java programming language and Jini.
There was a video interview of Gelertner by ZDnet. The three part interview is embedded below.