Director after director has struggled with the branding problem. Which is probably why the Saatchis, at the start of Elizabeth Esteve-Coll's stewardship in 1988, came up with the notorious slogan "an ace caff with quite a nice museum attached". Yes, we shrieked, but what sort of quite a nice museum? Under the present regime of her successor, the unregarded and soon-to-be-replaced Sir Alan Borg, more has happened than you might imagine. Such as the enormous rebuilding exercise of the new British Galleries, to open in the autumn of next year. Such as the Canon Photographic Gallery, or this year's launch of a "contemporary programme" to attract a younger audience - and, of course, the commissioning of architect Daniel Libeskind to design the famous "Spiral" extension, which may even one day happen. Borg knows that museums gradually become invisible without a modern makeover, and the more eye-catching the better. He sees what I.M. Pei's glass pyramid has done for the Louvre in Paris, and he wants some of that. But he chose to announce the Spiral scheme simultaneously with compulsory entrance charges, and guess which got the media coverage?

Today, there is a new generation of curators coming through, exemplified by Jane Pavitt and Gareth Williams, responsible for Brand.New. They are young. They are clearly ambitious. While Williams has so far traced a conventional career path through the museum, Pavitt is an outsider, an externally-funded research fellow in Product Design and Museology. It is significant that, when you meet Pavitt and Williams, their talk is not of what the museum is, but of what it might become.

There are signs of change. People noticed, for instance, when the designer/architect Ron Arad, famous for his challenging chairs, was given an exhibition this summer running right down the central spine of the building, elbowing aside the medieval treasures, insouciantly annexing the space. You may or may not admire Arad's work - I do - but this kind of shake-up was exactly what the museum needed. When you walked into the museum, it seemed alive, when usually it feels like a crypt.

After this shock of the new, signing up Thomas Heatherwick to design Brand.New and contribute his own ideas on content was a smart move by Pavitt and Williams. Heatherwick is one of the most versatile young designers around. Given a meagre exhibition budget of £250,000 (and no sponsorship) he has devised a strong series of themed rooms. Most daring of these is the first gallery. There is no introductory text at all, and no objects. Instead you walk through a "field of brands" - flag-like images on stalks, waving like corn in the fan-assisted wind. The field rises into a hillside, and you walk into the hill where - in a dark, cave-like space - the information begins with "the power of the brand". Of course, this is much-trampled territory - we all know about Coca-Cola, we are all savvy about brand loyalty and brand image and brand manipulation - but here it is done in a very fresh manner.

In one gallery there are seven room-sized boxes, for instance, each dealing with one way brands are individualised, from authenticity (Levis) through loyalty (Manchester United surreally combined with the cutesy Japanese phenomenon of Hello Kitty) to conscience (Body Shop, Fair Trade goods, etc). In the largest, cube-shaped gallery ("Branding the Individual"), Heatherwick has mounted video monitors in what he calls "burrs" - spiky assemblages that appear to have picked up logos and brand images by trundling through the rest of the show. They show films of people who feel strongly about brands (among them a man who buys only Marks and Spencer and Skoda, and a little girl with a Barbie fixation). The final gallery, dealing with how brands are subverted, faked, and derided, is treated as though the walls were giant blister-packs of pills, each blister being a clear plastic display pod.

Although in the 1980s the V&A's pint-sized Boilerhouse Project (which later moved away and became the Design Museum) dabbled intermittently in this area, no exhibition of this type on this scale has previously been attempted here. It is not full of valuable objects, unless you count some costly designer-label goods or an original 19th century pair of jeans. It is to do with ideas about the commercial world today. Which is quite a Prince Albert sort of thing to attempt, when you consider that his Great Exhibition of 1851 was a huge international trade show. Will Brand.New save the V&A? Of course not. But it provides some hope.