Copyright only applies to the original "work" be it text, pictures, artwork or some other form of creation. If you take the original text and republish it verbatim (without changes) you are clearly in breach of copyright. If you do as you say (re-spin it) then technically it's no longer the copyrighted work, it's now yours.
While this is all easy to understand, there is a "grey area"...
- If you copy & respin content (articles) from a large content site like eHow.com then expect to get some form of legal action, they're really protective of anything they suspect is their content
- If you copy & respin content from *lots* of small bloggers, independent writers and smaller content sites you are far less likely to get caught or encounter any legal issues