This question came up at session 3 of Websites 101, May 2013: Who owns the copyright to your blog postings, you or Blogger?
Both Blogger and WordPress say that you’re the owner of your content and will help you if you feel someone has violated your copyright. However, they reserve the right to use your content to publicize their own services.
Here is the relevant information from Google’s Blogger terms of service:
Your Content in our Services
Some of our Services allow you to submit content. You retain ownership of any intellectual property rights that you hold in that content. In short, what belongs to you stays yours. [Italics added.]
When you upload or otherwise submit content to our Services, you give Google (and those we work with) a worldwide license to use, host, store, reproduce, modify, create derivative works (such as those resulting from translations, adaptations or other changes we make so that your content works better with our Services), communicate, publish, publicly perform, publicly display and distribute such content. The rights you grant in this license are for the limited purpose of operating, promoting, and improving our Services, and to develop new ones. [Italics added.]
In other words, Google itself may reuse your material but only to promote Blogger or one of its other services.
What If Someone Steals Your Posts?
If you think someone has infringed on your copyright by reprinting your blog posts without asking you for permission or crediting you, you can ask Google to take the infringing material down.
On WordPress, check Content Theft–What to Do for more information if you think a WordPress blogger has stolen your material.
If you’re very concerned that someone has infringed on your copyright, talk to an intellectual property lawyer such as Oscar Michelen, who has given very informative talks about copyright at Staten Island’s West Brighton Community Local Development Corporation.