Alvin Gouldner is a not-very-well-known Marxist scholar who applied the Marxist dialectic to Marxism itself.
The Marxist dialectic is the method Marx proposed to dissect competing ideologies and uncover the hidden self-interests of their proponents. This is the way that Marxists approach their criticisms of capitalism, always looking, for example, for the ways in which the proponents of capitalism benefit from it to the deteriment of other citizens. Gouldner essentially applied the same sort of criticism to Marxism and its supporters.
One of the conclusions possible from Gouldner's exercise is that Marx was wrong in thinking that the propertied classes would be trashed by history for becoming an impediment to productivity. The alternative conclusion possible from Marx's own scientific method is that private property is necessary for human progress. There is plenty in Marx's own writings to support this conclusion, and it is only with a mighty effort and some questionable logic that Marx reaches the "correct" conclusion on that subject.
Although you will hardly ever catch a member of the doctrinaire left writing about it, it has been no secret that centralized economies have not done well in the last 100 years, and this has led a few socialists to consider pro-market forms of socialism. Gouldner offers that there is actually a rationale within Marxism that justifies this approach.
Of course, the idea of pro-market socialism is anathema to most of the left. After all, the whole point of Marxist socialism is that Marx's father and all those other bourgeoisie capitalists are scientifically condemned by history to inevitably get what's coming to them. Admitting that private property is good or necessary is too much of a capitulation for any good leftist to suffer.
However, it may be time for the left to think in terms of reform of rather than overthrow of market economies as their goal. They may possibly be beginning to arrive at this conclusion as a matter of necessity since even catastrophies like the Enron debacle have not stirred many people to seriously question market economies.