Web 2.0 applications expose organizations to both inbound and outbound security threats which transcend the legacy security measures created for Web 1.0.  The new generation of emerging security threats now consists of malicious attacks by cyber criminals targeted at specific organizations for personal or financial gain. 

This paper outlines these new threats and discusses the limited effectiveness of reactive legacy Web security solutions against those threats.  The paper then outlines the new reputation based, proactive security paradigm that is necessary for securing Web 2.0 applications and protecting the enterprises that use them.