Here's a description of the "Safe Harbor" provision of the 1998 DMCA, which allows sites like YouTube and Pinterest to operate without (too much) fear of copyright lawsuits.
Big news today: a ten-year-old lawsuit about Google Book Search has been resolved in Google's favor -- basically, the law has ruled that it was okay for Google to scan in-copyright books because it had no plans to publish the whole version of those in-copyright books online in http://books.google.com. Compare this to what we've heard about celebrity photographs and Pinterest. Here's a quotation from the story:
"When Google started work on its book search engine a decade ago, the company realized that getting the approval of copyright holders would be a logistical nightmare. Not only would major publishers likely demand high fees for permission to scan their books, but for many older works, it would be difficult to even figure out who the appropriate copyright holder was. So Google took a gamble, scanning library books without seeking copyright holders' permission and relying on copyright's fair use doctrine as a justification."
This is an article on the DMCA, so it may shine some light on my presentation yesterday on Pinterest and the copyright laws! It is also an interesting read and very informative!