And, in a country where art (as in television) and life have a habit of blurring, the real "Ellen", the writer and star of the show, Ellen DeGeneres, has also "come out", ending protracted rumour-mongering about her homosexuality.
Having decided to go public about her private life - several months after the show was planned, but only weeks before it is screened - the real Ellen is making the most of it. She was on the cover of Time magazine two weeks ago; she had an interview in ABC television's main personality slot, 20/20, this weekend and appears today, shortly before the crucial episode goes out, on the Oprah Winfrey talk show.
Most daring of all was her arrival at one of Washington's chief social events of the year - the White House Correspondents' Association dinner on Saturday - with her friend, the rising Hollywood star, Anne Heche, on her arm and occasionally around her neck.
Ellen Morgan's "coming out" on this evening's special hour-long episode of ABC television's Ellen is almost as star-studded - Oprah Winfrey plays the role of a psychotherapist and the openly lesbian country and western singer K.D. Lang is also featured.
To some, the popular response to tonight's programme will be "a kind of national referendum on the acceptance of "homosexuality" in America. But television is being cautiously smaller than life, caught in a melee of conflicting trends.
On the one hand, ABC television is both generating and revelling in the publicity. Ellen is currently running 35th in the viewing ratings, and going down. A boost is confidently expected from all the vast media fuss surrounding tonight's episode.
However, some of the local stations responsible for carrying ABC programmes to "heartland" America see Ellen's "coming out" as morally reprehensible and fear it could lose them ratings. A number have refused to carry the programme. Advertisers are facing similar problems.
Although television critics have counted as many as 35 gay characters appearing in shows down the years, this is the first time a female lead has acknowledged that she is homosexual and risks remain.
For ABC, there is the risk that ratings for Ellen may decline after the first flush of interest. For Ms Degeneres, acknowledged as a gifted writer and comedienne, there is the risk of being pigeon-holed as a "gay" star.
For gay rights campaigners, who have planned a series of "coming out" parties to coincide with the show, there is the risk of a backlash. As for Anne Heche, people are saying that, at 27, her Hollywood future may be doomed.