Recently Paul Andrews, technical product manager for identity management with Office 365, wrote a great blog article on how to setup the Windows Azure Active Directory Sync Tool (DIrSync) for your Office 365 deployment. I highly recommend this article for any organization that is interested in deploying any Office 365 services, including Office 365 Professional Plus or Office for iPad.
From his post:
If you’re just getting started with Office 365, you’re probably considering how to extend the user directory that you use for accessing internal resources for connecting to cloud resources. The simplest way to achieve this is with the Windows Azure Active Directory Sync Tool (DirSync). This tool runs on a Windows Server machine on your network and synchronizes users to the cloud. DirSync has a wizard-driven install and can be set up in just a few minutes. You should be able to synchronize your directory to Office 365 in under a day.
You can read the full post on the Office Blogs web site here.