Postmodern jokes are becoming a bit post-postmodern these days. One wonders how long it will be before jokes come back, and whether we'll understand them if they do. In the meantime, there's plenty more mileage to be had from savage irony, which turns out to be as nutritious as spinach in today's televisual world.

The emergence of Chantelle Houghton as the 2006 winner of Endemol's Celebrity Big Brother (Channel 4) adds yet another new convolution to the intricate masquerie of reality TV. It often has to be explained to me who 75% of the participants are on any show with 'celebrity' in the title. I haven't ever read the right columns, and it's far too late to start now. This one's famous because she has unconvincingly denied having an affair with a Premiership footballer. Another's fame derives from the ten months he spent in a band that had one middling hit before splitting in acrimony. But then the whole point is that, if they were more famous than this, they wouldn't need to go on celebrity reality shows. It isn't quite true that nobody at the peak of their renown is involved, but there is a disproportionate admixture of the ex-famous and the half-famous mixed in with the soap stars and Germaine Greer.

Chantelle is neither ex- nor semi-famous. She is pre-famous, or at least she was until this week. Now she is famous. And will fairly soon, no doubt, be ex-famous. What matters is that it doesn't matter. Celebrity reality shows are deconstructing the whole concept of fame in a more ruthlessly efficient way than even spoof news shows ever managed. When Brass Eye proved that you could get the famous to demean their fame by credulously giving their names to any apparently worthy cause - no matter how blindingly preposterous - a complex and instructive point was made about the nature of being in the public eye, the opportunities and responsibilities it throws up, and most of all, what attitudes it leads the famous to have towards the nonentities. Celebrity Big Brother isn't half as vindictive as that, but appears to be mining fresh and surprising nuances from the whole grubby business of the production and reception of fame.

A group of the famous have been made, over the course of the last few weeks, to accept a happy, smiley girl off the streets as one of their own. Her victory perhaps shouldn't surprise us because we like an underdog, especially one from Essex, and while we quite enjoy razor-tongued cattiness when delivered with the Scouse aplomb of a cosmetically reconstructed ex-pop star, we ultimately like to see politeness triumph over rancour, and sweet smiles win the day over comedy lips that look like they'd burst if you sprinkled salt on them. Plus, it's not hard to see which way the lad vote went on Friday night.

But let me get this right. A non-celebrity has won the celebrity version of Big Brother. Presumably she wouldn't now be eligible for the other Big Brother series in the summer, the one that features non-celebrities who are on their way to becoming celebrities. I don't pretend I don't understand this, and nor do I think it a force for evil in a world with Kim Jong-Il in it. While I have no interest whatsoever in sitting through the nightly transmissions from the Endemol house, it's less because I think it's beneath me, and more because it feels like being stuck in a lift with people who won't shut their yaps. Julie Burchill puts a lack of interest in Big Brother down to rancid snobbery. 'Is it all too too ghastly for you, darling?' she asked me last year. Not ghastly, just brain-shreddingly boring. George Galloway has not become one iota more interesting or forgivable for having engaged in an act of public humiliation with Rula Lenska.

If I'd had £1.50 to waste on a text vote last night, I'd have voted not for Pete Burns, whose 1980s turn in the sun was indeed a thing of beauty, but for that boy I'd never heard of from the Ordinary Boys, whose songs I've never heard. I only saw the final, by the way. But then that of course is the other post-postmodern thing about reality TV. You don't have to watch it to know what's happening. This too is an advance for contemporary culture.