It's been possible for years to change the default number of Google results in your browser to 100. Google has examined changing the number of results displayed, but changing that results in higher page load times for users. Even adding as little as 100 ms to the search results decreased the number of searches a user did a day on that engine (http://code.google.com/speed/files/delayexp.pdf).

Here are notes from talks by Marissa Mayer and experiments google did with 10, 20, and 30 results. It's quite interesting how people said they wanted more results, but testing showed that 10 results was better. http://perspectives.mvdirona.com/2009/10/31/TheCostOfLatency.aspx

I covered something very similar in my blog recently. It's quite easy to set your Google results list to 100. I switch back and forth between 100 and 10, depending on what I'm looking for. With longer results sets, nested listings can skew what you are seeing dramatically. As kerimogret mentioned, longer load times will likely ensure we never see 100 results as the Google default.

Part 1 of the post explains how to set your results list to 100.

Part 2 explains nested listings and how to work with them.