Web 2.0 is an umbrella term coined to include technologies used for providing user-centric web based services. Here, the services are architected and programmed so that they can be personalized and used dynamically. The architectural philosophy is called Service Oriented Architecture (SOA).
This document provides security aspects for Web 2.0 based services. It provides a list of threats that need to be considered for mitigation when deploying Web 2.0 services as well as ideas on how to deal with them.
Download the paper in PDF format here.