On 9 October 1967, Che Guevara faced a shaking sergeant Mario Teran, ordered to murder him by the Bolivian president and CIA, and declared: "Shoot, coward, you're only going to kill a man." The climax of Stephen Soderbergh's two-part epic, Che, in real life this final act of heroic defiance marked the defeat of multiple attempts to spread the Cuban revolution to the rest of Latin America.

But 40 years later, the long-retired executioner, now a reviled old man, had his sight restored by Cuban doctors, an operation paid for by revolutionary Venezuela in the radicalised Bolivia of Evo Morales. Teran was treated as part of a programme which has seen 1.4 million free eye operations carried out by Cuban doctors in 33 countries across Latin America, the Caribbean and Africa. It is an emblem both of the humanity of Fidel Castro and Guevara's legacy, but also of the transformation of Latin America which has made such extraordinary co-operation possible.

The 50th anniversary of the Cuban revolution this month has already been the occasion for a regurgitation of western media tropes about pickled totalitarian misery, while next week's 10th anniversary of Hugo Chávez's presidency in Venezuela will undoubtedly trigger a parallel outburst of hostility, ridicule and unfounded accusations of dictatorship. The fact that Chávez, still commanding close to 60% popular support, is again trying to convince the Venezuelan people to overturn the US-style two-term limit on his job will only intensify such charges, even though the change would merely bring the country into line with the rules in France and Britain.

But it is a response which also utterly fails to grasp the significance of the wave of progressive change that has swept away the old elites and brought a string of radical socialist and social-democratic governments to power across the continent, from Ecuador to Brazil, Paraguay to Argentina: challenging US domination and neoliberal orthodoxy, breaking down social and racial inequality, building regional integration and taking back strategic resources from corporate control.

That is the process which this week saw Bolivians vote, in the land where Guevara was hunted down, to adopt a sweeping new constitution empowering the country's long-suppressed indigenous majority and entrenching land reform and public control of natural resources - after months of violent resistance sponsored by the traditional white ruling class. It's also seen Cuba finally brought into the heart of regional structures from which Washington has strained every nerve to exclude it.

The seeds of this Latin American rebirth were sown half a century ago in Cuba. But it is also more directly rooted in the region's disastrous experience of neoliberalism, first implemented by the bloody Pinochet regime in the 1970s - before being adopted with enthusiasm by Margaret Thatcher and Ronald Reagan and duly enforced across the world.

The wave of privatisation, deregulation and mass pauperisation it unleashed in Latin America first led to mass unrest in Venezuela in 1989, savagely repressed in the Caracazo massacre of more than 1,000 barrio dwellers and protesters. The impact of the 1998 financial crisis unleashed a far wider rejection of the new market order, the politics of which are still being played out across the continent. And the international significance of this first revolt against neoliberalism on the periphery of the US empire now could not be clearer, as the global meltdown has rapidly discredited the free-market model first rejected in South America.

Hopes are naturally high that Barack Obama will recognise the powerful national, social and ethnic roots of Latin America's reawakening - the election of an Aymara president was as unthinkable in Bolivia as an African American president - and start to build a new relationship of mutual respect. The signs so far are mixed. The new US president has made some positive noises about Cuba, promising to lift the Bush administration's travel and remittances ban for US citizens - though not to end the stifling 47-year-old trade embargo.

But on Venezuela it seemed to be business as usual earlier this month, when Obama insisted that the Venezuelan president had been a "force that has interrupted progress" and claimed Venezuela was "supporting terrorist activities" in Colombia, apparently based on spurious computer disc evidence produced by the Colombian military.

If this is intended as political cover for an opening to Cuba then perhaps it shouldn't be taken too seriously. But if it is an attempt to isolate Venezuela and divide and rule in America's backyard, it's unlikely to work. Venezuela is a powerful regional player and while Chávez may have lost five out of 22 states in November's regional elections on the back of discontent over crime and corruption, his supporters still won 54% of the popular vote to the opposition's 42%.

That is based on a decade of unprecedented mobilisation of oil revenues to achieve impressive social gains, including the near halving of poverty rates, the elimination of illiteracy and a massive expansion of free health and education. The same and more is true of Cuba, famous for first world health and education standards - with better infant mortality rates than the US - in an economically blockaded developing country.

Less well known is the country's success in diversifying its economy since the collapse of the Soviet Union, not just into tourism and biotechnology, but the export of medical services and affordable vaccines to the poorest parts of the world. Anyone who seriously cares about social justice cannot but recognise the scale of these achievements - just as the greatest contribution those genuinely concerned about lack of freedom and democracy in Cuba can make is to help get the US off the Cubans' backs.

None of that means the global crisis now engulfing Latin America isn't potentially a threat to all its radical governments, with falling commodity prices cutting revenues and credit markets drying up. Revolutions can't stand still, and the deflation of the oil cushion that allowed Chávez to leave the interests of the traditional Venezuelan ruling elite untouched means pressure for more radical solutions is likely to grow. Meanwhile, the common sense about the bankruptcy of neoliberalism first recognised in Latin America has now gone global. Whether it generates the same kind of radicalism elsewhere remains to be seen.

s.milne@theguardian.com