The word was introduced on Kotaku (a gaming blog) in a December 07,2005 blog entry titled "Want to know Madonna's 360 thoughts". The word refers to celebrity impersonators who pose as celebrities by writing blog entries from their point of view.
In short, a celebriblogenator is "a ghost author assuming the guise of a celebrity through the use of a blog written from the celebrity's viewpoint" (quoted from Sederien, a Kotaku reader)
Sony Fanboy: Hey check this out Madonna says Xbox 360 sucks! LOLOLOLOLz!!11!!!1oneoneone
Smart Dude: Nah, it's prolly just a disgruntled celebriblogenator trashing the 360.