You use Google to search every day, you improve their search results, you store your mails on Google's servers and a lot of other data. What if one day you discover other company that provides better services and you want to move all your data? Google's CEO, Eric Schmidt, thinks that will be possible in the future: "We are working to ensure that as long as it is yours, we want to give you the equivalent of number portability. Data should never be held hostage. We might as well get ahead of it before a law gets passed forcing us to do that."
For the moment, there isn't an easy way to export your mails from Gmail to Yahoo Mail, for example or to export your posts and comments from Blogger to WordPress. Google usually promotes choices and making easy to switch to other competing services would be a logical step. If you think your services are the best and you respect your users, you shouldn't be afraid of the competition.