Many blogs have grown popular by leaps and bounds which consist mainly of, or solely of, hundreds of beautiful images uploaded via image URL, without permission by the image copyright holder. As innocent an act this is there may be a piper to pay one day for doing so, and it won't be cheap!
There is new web bot technology which is very hot right now, and companies are using it for their clients who wish the bots to crawl the web and seek out their images on websites, blogs, and social websites that are posted without their permission. I suppose we have become too comfortable posting any image with merely a image source or include disclaimer pages, but this will not protect us from lawsuits, take this from Roni Loren (see below.)
Included below are two very good links with information on this subject, and I URGE you to read them both. The second is a first-hand account of what happened to writer, Roni Loren.
- Copyright infringement, extortion and scams - via bosshi.com
- Blogger Beware: You CAN Get Sued For Using Photos You Don't Own on Your Blog - by Roni Loren blogher.com