To chime in with my two cents, it appears to me that capitalism is not failing. What I do see is the middle class losing ground to the upper class, and siding with their soon to be peers, the lower class. Eventually the 3 groups polarize will completely, and the paupers will oust the princes.
Marx FTW! Seriously, I can see society diverge into two truely distinct layers due to technological or economical developments, but thats not whats happening today.
Whats happening today is in fact a massive increase in equality between the western marginally productive worker and the vast numbers of actually poor people eager to take their subsidized jobs. The supply of low-skilled labor has expanded enormously, and the supply of capital and high skilled workers relatively little. That is to be expected when most of the world is quite busy pulling themselves out of the dark ages. But this trend is probably already on the decline; now its china being asked to bail out europe. Their stocks of (human/technological) capital are growing, and its increased supply will make it relatively difficult to continue the trust-fund lifestyle that we have been enjoying; especially for those most reliant on it (the very very rich).