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I would be happy to provide you with some documentation links.
For basic info on Identity Federation check out "Single sign-on: Roadmap" at http://onlinehelp.microsoft.com/en-us/office365-enterprises/hh125004.aspx.
“Identity federation implementation guide for the Office 365 environment” at http://support.microsoft.com/kb/2530569 is an awesome document with lots of details including how to validate and troubleshoot for each step.
Are you planning on using co-existence? Do you have a migration plan? Check out this document:
"Exchange Hybrid Deployment and Migration with Office 365" at http://help.outlook.com/en-us/beta/ff633682.aspx, which has a good overview of the various co-existence and migration types.
Check out the Exchange Server Deployment Assistant at http://technet.microsoft.com/en-us/exdeploy2010/default.aspx#Index. This will create a custom doc with lots of details on migrating to the cloud. You can get a printout by using the Download Checklist link after answering the questions.
Give these a try and let us know if you have more questions.
Todd Douglass - MSFT Support Engineer