Virtual world research firm KZero has recently released their latest figures on the populations of virtual worlds, broken down by age group. The big news is that they report that there are now over 1 billion registered accounts across all worlds they surveyed, with over half of those in the 0-15 year old age bracket.
For educators and institutions making a case for the continuing relevance of virtual worlds, the "1 billion" figure is a nice round figure to tell people. And the giant and growing youth market is helpful for educators in particular.
See more on the Kzero website.