Progressive politics is an alternative to conservatism but not as far to the left as socialism. Progressive politics is about social justice and workers rights. Franklin D Roosevelt was a progressive. Of course we have shifted so far to the right nowadays, and the left is so weak and divided, that hardly anyone dares mention socialism (or even social democracy) anymore.
'Progressive' has been co-opted by 'modern' political parties because it sounds good - i.e. forward looking - and, for parties of the 'left', avoids using the dreaded 's' word. But being 'progressive' has to be a pretty vacuous concept if it is being used by New Labour and the Tories. Of course, neither the Tories or New Labour are progressive parties in the true sense of the word - they both espouse reactionary free market policies. The reactionary right are trying to co-opt the term progressive to describe their politics thereby devaluing it as a concept, just as they have stolen to term 'reform' which means 'making things better'. Does this matter? Well yes it does because it confuses people and provides yet another distraction from the issues that we should be talking about.
I think socialism's obituary has been written far too soon. But its interesting to read 'lefties' squabbling on CiF about what left wing politics means nowadays. What they need to understand is that nothing has changed - the same old conflict between Capital and Labour is continuing as it always has. Class is just as important as it ever was, and good old imperialism is going strong too - they just call it globalisation these days. All this has been well understood for well over a century thanks to someone called Marx, and others. Give these 'lefties' a couple of decades and they might manage to come up with some coherent ideas for a way forward and ... er ... call it socialism.