Eric Wolfram writes an enlightening article to help all web developers:
Almost everyone searches Google to find information, and Google quickly rewards them by displaying the information they are seeking. Thereby, Google rewards useful sites with the eyes of people who are looking for useful information. This is helping the web recover from being the wasteland of marketing hype, which the dot-come-and-gone explosion forced it to become. Google is saving the web by ultimately forcing site designers to make their sites useful again.
By being useful, Eric means linking to sites outside of your own. By doing this you help the “web” live up to its name by letting it be just that, a web of information. Blogging by its very nature lends itself very nicely to Google. But corporate sites whose policy is to not link to external sites are going to find it hard to attain a worthwhile ranking in Google unless they change their tactics.