This presentation by Robert Gillies, Understanding Microsoft Forefront Online Protection for Exchange, which was recently posted on Channel 9, is a good introduction to the product for a system administrator or technical manager. It's helpful if you are new to FOPE, or are just considering it. He covers the following:

• FOPE's service level agreement
• Overview of FOPE and its architecture
• anti-spam - what FOPE protects against
• Inbound filtering details - block lists, and so on
• Outbound filtering, for viruses, spam, and so on
• Signing up for a free trial
• Setup and provisioning
• A demonstration of FOPE administration
• Reporting
• Junk Mail Management
• FOPE Inbound and Outbound Connectors
• Policy Enforcement
• Exchange Hosted Encryption