The fifth Big Brother has been notable for its firsts: the first stand-up fight (amid tabloid hype and cries from the chattering classes that TV had finally gone too far); and the first time live sex had been broadcast, when Stuart and Michelle fumbled noisily under a table for an hour.
But while the show is still the highest-rating programme on Channel 4, it's already old news in television and, having broken so many taboos, it's hard to know how long it will remain so enormously popular.
Some in the TV industry are calling for Channel 4 - with its remit to innovate - to do more than just recycle tried and tested ideas. But, crucially for the advertiser-funded channel, Big Brother continues to rack up ratings and advertising revenue.
"The point about innovation is that when we get something right it can be commercially successful," says a Channel 4 spokesman. "We can't afford to walk away from those successes but we do have to keep innovating across the rest of our schedule."
Those charged with pushing the envelope are the channel's suppliers: independent producers who aren't owned or operated by broadcasters and who spend all day dreaming up programme ideas to pitch to commissioning editors.
Ruth Wrigley, former Big Brother producer and now head of factual entertainment at producer Talkback, reckons it's time for a move to less exploitative programming featuring real people.
Specifically, she's against the proposed sperm race show in which men compete to see who can father a child fastest, or The Swan, a format from the US in which a so-called ugly duckling is transformed with the help of plastic surgery.
"I'm not sure it's ethically right to say you're a fat ugly cow," says Wrigley. "These programmes have become more and more extreme, and there are certain things that I wouldn't want to work on now. Although Big Brother came under a lot of fire when it started, I believed it was an interesting proposition in which consenting adults took part in something of an experiment."
Wrigley is working on an idea that is "quite radically different" from either Big Brother or ITV's reality hit I'm A Celebrity, Get Me Out of Here. "We'll still use real people but in a way that they get something out of it," she explains. "We'll go with the flow and give them a framework rather than impose something like a task on them."
Hat Trick, maker of Have I Got News for You, is also working on "more humane" reality shows, according to its head of entertainment, Leon Wild. "We're looking at more inclusive formats where the end result is slightly more worthwhile than just watching people for your own sordid pleasure," he says. He points to reality programmes featuring older people and married couples: "I wouldn't be surprised to see some feel-good formats where nice things happen to people," he says.
RDF Media, the company behind Wife Swap, is hoping its new show, The Block, which launched on ITV last week, will be the next big thing. Based on a Scandinavian format, The Block has already aired for two successful series in Australia and features couples competing to renovate and win their dream home.
Producers are also looking to export ideas, as well as import them. RDF has an American version of Wife Swap going out on the ABC network this autumn. Mentorn, part of The Television Corporation, struck gold earlier this year when it won a commission from the Fox network for Paradise Hotel, a format in which people compete to win a stay in a luxury hotel.
A glance at the track records of the most successful independent production companies reveals that any TV company which wants to hit the big time must have an entertainment hit in its portfolio. Hence Lion Television, traditionally a producer of high-end factual programming whose previous claim to fame was as the producer of Castaway 2000, has diversified into entertainment with Playing It Straight, a format for Fox in the US in which a single woman attempts to find her ideal mate from a group of straight and gay men.
Lion's joint managing director, Richard Bradley, is hoping China will be the next proving ground for new ideas. He hopes to export lifestyle TV formats from the UK. "There's a huge Ikea in Beijing and the biggest B&Q in the world outside Shanghai, and we're seeing the first generation that can legally own property," he explains.
His approach proves that being in touch with the zeitgeist, wherever that may be, is the final, key criterion for spotting the next big thing in TV.
Chief executive: Peter Fincham
Hits: Pop Idol, The Bill, How Clean is Your House?
The most valuable independent producer of TV formats, created out of a £62m merger in 2000.
All3Media including Lion Television
Chief executive: Steve Morrison
Hits: Midsomer Murders, Richard & Judy
Formerly Chrysalis TV Group but renamed after a buyout by ex-Granada executives Steve Morrison and David Liddiment.
Chairman: Peter Bazalgette
Hits: Big Brother, Fame Academy, Restoration, Changing Rooms, Ground Force
Peter Bazalgette started Bazal Productions in the 1990s. A merger with Netherlands-based Endemol in 1998 added Big Brother to its roster.
Chief executive: Jeff Foulser
Hits: Paradise Hotel, Robot Wars
Includes Channel 4 cricket producer Sunset & Vine, and benefits from a diverse range of output that includes BBC 1's Question Time.
Chief executive: David Frank
Hits: Wife Swap, Scrapheap Challenge
Hit the big time with award-winning factual format Faking It and hasn't looked back.