Another great IBM RedBooks publication about "new" MQ features, the headline in v7.1/7.5 was in my optics:

• Enhanced security
• Channel authentication records: Controlling remote user activity
• Shared message data set and message offloading (z/OS)
• Coupling facility connectivity loss improvements (z/OS)
• Extended integration with IMS (z/OS)
• and more

You find the RedBook here: http://www.redbooks.ibm.com/abstracts/sg248087.html

Introduction video

Table of contents

Part 1. Introduction
Chapter 1. Overview
Chapter 2. Concepts of messaging
Chapter 3. Introduction to WebSphere MQ
Chapter 4. Getting started with WebSphere MQ
Chapter 5. What is new in WebSphere MQ V7.1 and V7.5
Part 2. WebSphere MQ 7.1 new features and enhancements
Chapter 6. Installation enhancements in WebSphere MQ V7.1
Chapter 7. Multiple installation support on Windows, UNIX, and Linux
Chapter 8. Enhanced security
Chapter 9. Granular control over Dead-Letter queue usage
Chapter 10. Dumping and restoring a queue manger configuration
Chapter 11. Shared message data set and message offloading (z/OS)
Chapter 12. Coupling facility connectivity loss improvements (z/OS)
Chapter 13. Extended integration with IMS (z/OS)
Chapter 14. CSQINPT DD added to queue manager startup JCL (z/OS)
Chapter 15. CICS 4.2 group attach (GROUPUR)
Part 3. WebSphere MQ 7.5 new features and enhancements
Chapter 16. Installation enhancements in WebSphere MQ V7.5
Chapter 17. Clustering enhancements on Windows, UNIX, and Linux
Chapter 18. Certificate validation policies
Part 4. Scenarios
Chapter 19. Coexistance: A staged migration on Windows, UNIX and Linux
Chapter 20. Channel authentication records: Controlling remote user activity
Chapter 21. Clustering: Multiple cluster transmission queues
Chapter 22. Shared queues: Exploiting the new capabilities
Chapter 23. GROUPUR: Exploiting group units of recovery with CICS
Chapter 24. Resiliency: Improving availability
Appendix A. MQSC scripts for the coexistance scenario
Appendix B. WebSphere MQ for z/OS 7.1 System Management Facility changes
Appendix C. Additional material