Just recently EPN published the promised update on their previous report into the use of Second Life. (Dutch pdf) The new report is called: "Residents in analyse : De feiten over Second Life na de hype" and is again written by David de Nood & Jelle Attema.
For some reason they do not offer the pdf online, but ask you to request it via EPN, firstname.lastname@example.org. I hope we can expect the english edition soon, freely available. Here's some Dutch info on the press release.