Google can often tweak their Webmaster Guidelines, but as SEO is such a huge industry these changes are rarely missed. Even something as little as adding a line of text to a paragraph.
Which is what Google have done in their quest to define spam. As we all know, Matt Cutts has very strong opinions when it comes to Guest Blogging. And now we can see that Google as a whole are taking issue with guest blogging too. Check out the Before and After Images below that shows the change in webmaster guidelines:
Blog Post by: Greg McVey