If you are a Microsoft Partner, the following guide from Jesper Osgaard is an excellent introduction to establishing a practice around Office 365.
Office 365 is having a tremendous momentum. As a Microsoft Partner with customers looking at Office 365 this is the guide for you. It includes links to important e-learning, documentation, kits and other material intended to help you get started with your Office 365 practice.
You can access the guide here.