What's interesting, though, is that it's not universal, even in the English speaking world. In Canada, there's been an opposite trend - the three major political parties are now closer together than ever. The NDP shed a lot of its hardcore socialist trends under Jack Layton and, while still definitely left wing, is much more centrist now than in the years of Tommy Douglas. By the same token, the Conservatives moved left and appropriated a lot of the Keynesian economics that the Liberals were famous for (and the Liberals themselves cribbed some of the more successful Conservative pet projects, like free trade and an aversion to across-the-board tax increases).
That is interesting... I guess that the starting conditions for both countries would have a lot to do with it. Obviously can't entirely blame the internet either, but definitely at least shows that it's not a necessary effect of the internet ---