I was ego-surfing again, testing out a few of the newer search engines and I came across this blast from the past on a site called WordSpy, which tracks words and their origins.

"screenager (SCREE.nay.jur) n. A young person who has grown up with, and is therefore entirely comfortable with, a world of screens, particularly televisions, computers, ATMs, cell phones, and so on."

As an example of its use, it quotes a December 2002 article by Michael Snider using the term screenager.

The earliest citation of the word is in 1994 by guess who, quoting guess who:

"Meanwhile, new magazines are rapidly being launched to target the home market. Oakland-based Blast Publishing Inc. is preparing to launch a major national magazine called Blast, which, according to Publisher Doug Millison, will be a "lifestyle magazine aimed at 'screenagers', teenagers and twentysomethings that have grown up with PCs and video games."

—Tom Foremski, "Homes are prime PC frontier," The San Francisco Examiner, June 19, 1994"

Here is the full entry from Wordspy.

UPDATE: Doug Millison adds that "screenager" was actually coined by Dave Pola, sales and marketing honcho for Morph's Outpost, Inc. (which published the pioneering magazine for interactive multimedia designers and developers, Morph's Outpost on the Digital Frontier, from 1993 to 1995) and sister company, Blast Publishing, Inc. which published Blaster magazine. (The magazine was originally called Blast, but that was changed to Blaster, for intellectual property reasons, by the time the magazine launched.) Journalist, Doug Rushkoff, now a professor at NYU, helped to popularize the term "screenager," beginning in the column that he wrote for Blaster.