I’m putting together some FAQ links and thought I’d share a few resources right off the bat.

The Microsoft Office 365 Fact Sheet has details on what is included in each version and pricing.

The Office 365 Beta Service Descriptions provide details on SharePoint Online, Exchange Online, Lync Online, Office Web Apps and Office Pro Plus Beta services. 

For us as developers, I think the most important thing is the feature list and feature comparison versus the on-premises versions.