Gerald Block writing in the "The American Journal of Psychiatry" considers internet additiction to be a "compulsive-impulsive spectrum disorder."

Link:
Issues for DSM-V: Internet Addiction -- Block 165 (3): 306 -- Am J Psychiatry

Some countries already have rehab facilities for those that are addicted to the internet:

http://www.nytimes.com/2007/11/18/te...hp&oref=slogin

Rehab is even available in the United States for those with internet addictions:

Is Internet Addiction the Socially Acceptable Drug of the 21st Century? | The Canyon