The Times credits the local tech columnist who (as we said) first identified YouTube star LonelyGirl15:

Matt Foremski, the 18-year-old son of Tom Foremski, a reporter for the blog Silicon Valley Watcher, was the first to disinter a trove of photographs of the familiar-looking actress, who portrayed the character named Bree in the videos.

Way to go, Foremski boys! We knew Tom (a well-known Valley dude and a former Financial Times reporter) was due for a scoop, but this was a shocker. (And since we assume the discovery involved poring over photos of cute teenage actresses, we're relieved Tom's 18-year-old-son did the legwork.)

Well, It Turns Out That Lonelygirl Really Wasn't [NY Times]
SVW Exclusive: The identity of LonelyGirl15 [Silicon Valley Watcher]