A new Redbook on Sametime 7.5.1 has been published:
Sametime 7.5.1 – Best Practices for Enterprise Scale Deployment

In short: “This IBM Redbooks publication provides a best practice framework for an enterprise-scale deployment of Sametime 7.5. It covers a range of business collaboration requirements that might typically be found within many large enterprises with geographically dispersed user communities and diverse business requirements for real-time collaboration.“