I've already posted a series of updates on social networking and web 2.0, as well as enterprise 2.0, management 2.0 and knowledge management 2.0.
I like Jane Hart’s description of learning 2.0 as well:
“Learning 2.0 (or E-Learning 2.0) is a second phase of (E-)Learning based on Web 2.0 and emerging trends in learning e.g. informal learning, self-managed learning and performance support.
The traditional model of Learning (which might be termed Learning 1.0) focused on content produced by experts (teachers, instructors, etc), and structured into courses, to be consumed by users/learners.
Web 2.0 technologies support a more social, collaborative and sharing approach to learning, so that learners (in both formal and informal learning situations) can co-create content and collaborate with peers to form a learning network - hence it is also referred to as Social Learning.”