You'll have seen by now Duncan Watt's groundbreaking NYT article on the subject of cumulative advantage; you should read the article if you want to understand how the world works, but commentary and summaries also appear here. Mathew Ingram offers probably the most lucid summary: "if someone is popular - for whatever reason, be it real talent or just
blind luck - he or she is likely to become even more popular, since
people tend to gravitate towards things that are already perceived as
being popular". And as Scott Karp points out, this means that MySpace isn't the most popular social network because it is in some way inherently the best - it is the most popular because a handful of decisions by the earliest adopters were randomly amplified by subsequent adopters.
If the theory is true - and it seems obvious that it is, not least because it has cropped up before in various guises - It raises an additional question for me. What happens in systems where the first mover is not determined randomly? Or to put it another way - given this research, how much does the first mover advantage enjoyed by Hart's Location and Dixville Notch really let their 56 voters determine the outcome of US national elections?