
A few things to add to
Simon's list of the prehistory of Popism: 'popism' itself is increasingly not a particularly useful term, as it limits the critique to the Freaky Trigger/ILX/Poptimism axis, who contributed a fair amount of interesting debate once upon a time, and because this is a far wider phenomenon, extendible from Channel 4, to the Universities to New Labour. But here are a few early instances of the 'Popist' move (the consummated and unconsummated affairs between intellectuals, the avant-garde and mass culture), which also show a history that gradually degenerates into mere cheerleading for capitalism:

First and foremost, Eccentrism, a movement in 1920s USSR, basic theory being: 'slapstick comedies (Keaton, Chaplin etc) are superior to all previous Western art'. General popist valourising of all things American, commodified and so forth in their manifesto, which is
a really very exciting read. Meanwhile, my own short thing about them
is here. The differences are twofold with today's vastly less interesting version: a) political commitment (linked with general popist epatering of bourgeoisie but also 'aha, Laurel and Hardy are better than the Bolshoi' as workerist gesture and b) interest in using popcult to create the new and avant: Eisenstein, Modernist par excellence, was pals with this lot, and their own films were distinctly disjunctive as well as circus-populist. See also the work of Vesevelod Meyerhold, the craze for the 'Red Pinkertons' in the mid 20s, i.e detective novels with a Marxist-Utopian slant, often written by Formalist linguists such as
Marietta Shaginyan's Mess-Mend; and the bizarre attempts to create a 'Red Douglas Fairbanks' and so forth. In fact there's a whole
Russo-German leftist/intellectual appreciation for American masscult in this period that someone (that is, me) is going to write a thesis on.

Reyner Banham, principally in his book on LA and the delightful BBC film
Reyner Banham Loves Los Angeles, which is available on Google video, and whom I briefly discussed
here. A sort-of-Warholian/Ballardian cheering of the freeway, the strip and the billboard from Late-Modernist architecture critic. Like the above, this is more a Pulp Modernism which is superficially similar to but far more critical and intelligent than the actual phenomenon that K-Punk and others have critiqued. Pulp Modernism is unlike Popism in that it takes Popcult at its most disruptive, and most futuristic: taking the popularity of Sci-Fi, comics and fantasy as its pop launchpad as opposed to what actually
sells, which is a mixture of this and a fair amount of the entirely worthless.
Archigram are a fine exemplar of this trend, as were the
Independent Group, and Banham had links with both. See also
Streamline Moderne a few decades prior.

More akin to actual 'Popism' (or as yet unfinished new term) avant-la-lettre - Robert Venturi and Denise Scott-Brown's
Learning from Las Vegas, an early 70s anitmodernist urbanist tract. There are elements here that are more Pulp Modernist than Popist. The book divides roughly into two sections, the first on Vegas, which is more Pulp - the neon phantasmagoria of the garish and lurid billboards and the lettering on the casinos, the rippling 'Braziloid' Modern of Vegas' buildings and so forth. But the second part, 'The Decorated Shed', a call for the 'dull' and revivalist in architecture, is much more like 'Popism' as is, as can be seen in the little charts of oppositions that punctuate it: boring is better than interesting, consumerism is better than collectivism, advertising is better than art, the Client (read: consumer) is king, you know the drill - only here unlike in Warhol, Ballard and others it goes the whole hog into neoconservatism via the 'nothing interesting can happen anymore' mode and the attack on paternalism and the avant-garde leading to reclaiming of the straightforwardly, uncritically corporate: 'all that appears is good, all that is good appears', as Debord puts it.

The important point, for a rationalist theory of Pop, is the maintenance of the critical - popculture's ability to throw up all manner of excitement and brilliance is surely beyond dispute (albeit it's been having a distinctly lean few years), and despite postmodernists' self-aggrandisement on this one, this is something with a long avant-garde and Modernist (and politicised) history. Yet as has been pointed out, when we end up with
this sort of thing, an impasse has clearly been reached. Forgive me for my literalism, but isn't
this 'our Vietnam'??