Below is video of a presentation from DrupalCamp Dallas in which Randall Knutson provided insight into what Lifestreaming is and then shows how to create one using Drupal. The method Randall uses to create a Lifestream in Drupal is by using the Feed API module. Coincidentally I too have spent a good deal of time recently implementing this module for the X PRIZE website and also did a quick talk on it at the LA Drupal meeting this month (video should be available in the future).
The video is just shy of an hour and unfortunately the camera is focused on Randall as opposed to the projector which he appears to be using to show much of the process. Still it is worth listening to if you are interested in learning more about Lifestreaming and Drupal.
Randall also created a slide presentation which is available on Google Docs here.
While Feed API is a very powerful and flexible module, there is a simpler alternative for creating a Lifestream using Drupal. Be sure to also look at the Activity Stream Module written by Adam Kalsey which was designed specifically to create a Lifestream. It comes with support for a slew of services out of the box with the ability to create additional ones as well. Below is a screencast that shows how to install, configure, and use the module.