In reply to Clay Shirky (unfortunately I couldn't post as a reply there, as it kept returning an error about javascript and cookies)
We all live within an environment. Part of that is obviously our physical environment, but the bit I am writing about is our learning environment. Looking at what each of us, as an individual, uses to support our learning gives rise to the concept of a Personal Learning Environment, or PLE. The term PLE, however, is typically used with regard to the technological toolset an individual uses, rather than the sum of all factors in the learner's environment.
This is far from perfect, but listening to tweets while reading something else is about the best use of the spare audio channel in my brain I can think of at the moment!
This is written in Ruby, and uses the marvellous Twitter client from @jnunemaker (the Twitter gem)