Update: Oops! It seems that MediaDailyNews had it wrong, and that the June date wasn't when Nielsen would be getting the ratings out, but instead, just when it would be making another announcement about its progress to its clients.
Media Daily News' Joe Mandese has an update on the Nielsen "Extended Screen" system to measure online TV viewing, noting that beginning on May 16 Nielsen will begin releasing audience data (starting with the week of April 25) for shows even if they do not contain the same national promos or local ads as they originally aired on live TV. Ratings for shows that contained different national paid advertising are to be available sometime in June.
It's not clear how much of these new Extended Screen measurements *we* will get. If I had to guess, it will be limited to what comes in press releases from the networks themselves, similar to how we occasionally see information on the C+3 commercial ratings, but we'll have to wait and see.
But it now looks likely that the 2011-12 season will be the first in which it will be possible to get comparable online, Live and DVR TV viewing audience numbers from Nielsen.
One result of this is that I'd pretty much guarantee that by next Fall any online viewing available within 3 days of the airdate of any show will contain the same paid national advertising as the live broadcast.