Here are some fairly comprehensive yet short overviews of digital learning.
How Online Learning Is Revolutionizing K-12 Education and Benefiting Students (2010)
Dan Lips of The Heritage Foundation discusses how online learning differs from traditional learning, explains some of its potential benefits, discusses some evidence of its effectiveness, reviews the extent of digital learning in the U.S., and gives recommendations for state and local officials.
Virtual Schools: For Some, the Future of Education (2007)
John LaPlante (author of Kansaseducation.wordpress.com and at the time a policy fellow with the Flint Hills Center for Public Policy) describes the reasons why some students find virtual schools useful, and offers recommendations concerning public policy relating to virtual schools.