It is not possible to deploy the Office 365 platform to a private cloud environment, Microsoft is not licensing the specific technology they use to provide the Office 365 service.
If you want to host Exchange and SharePoint in your own datacenter for customers, you'll need to base your environment on the Server versions of the products and implement your own hosting-oriented framework around it to provide a hosting experience for your customers. This can be done, and is done by many hosting providers today. As for the specifics of how to do this, that's a pretty deep topic and its going to vary depending on the platform. I don't know Exchange, so beyond the fact that I know it's done quite a bit I don't know how its actually done. With SharePoint 2010, multi-tenancy is one of the new features added into the product that will help with enabling it, I'd suggest by starting with a look at that functionality.
But I'm sorry to say that there isn't an installer or anything for you to run to set up an Office 365 environment locally in your own environment.
MCITP and MCTS: SharePoint, Virtualization, Project Server 2007
My books on Amazon: The SharePoint 2010 Disaster Recovery Guide and The SharePoint 2007 Disaster Recovery Guide.
My blog: My Central Admin.
If you want to become an Office 365 partner start by going here: http://www.microsoftcloudpartner.com/us/default.aspx
You can get there through https://partner.microsoft.com as well.
- Proposed as answer by Daniel Trautman Tuesday, March 27, 2012 8:16 PM