Thought of sharing : summarized  process for transition from BPOS to Office 365  as many partners are having this question nowadays. See link below for  Transition guide –good one.

http://download.microsoft.com/download/F/E/B/FEB0E713-51CE-4896-9856-28D9B66FF124/BPOS_to_Office_365_Customer_Transition_Guide_4-26-11.docx

BPOS to Office 365 Overview

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The transition from BPOS to Office 365 does not represent a new version or product for Microsoft Online Services customers. Office 365 is an evolution of BPOS. The transition does, however, represent a major architectural shift for Microsoft’s Online Services architecture from on-premises servers adapted to the cloud, to a fully-rearchitected service-oriented design. This is the reason that there are some impacts in terms of system requirements and configuration of optional features such as federated identity and rich co-existence.

One of the key values of Microsoft Online Services is that customers are not required to re-deploy or upgrade server software, nor are they required to migrate data when new features and capabilities are available or services are updated. This will hold true for the transition process that enables the new features and capabilities of Microsoft Office 365. All server infrastructure updates and data migration will be handled by Microsoft. Microsoft is committed to ensuring that the transition from BPOS to Office 365 is simple for customers, will minimize disruptions to end-users, and will maintain the security and integrity of customer data at all times.

The underlying 2010 server technology that drives Office 365 was architected to run as a service in the cloud and to enable seamless updates to the service. This new architecture means that future major service updates to the Office 365 service should have an even lower overall impact on customers than the transition from BPOS to Office 365.

The attached  guide includes information that existing BPOS customers will need to prepare for the transition from BPOS to Office 365. Trial customers and customers who have not yet deployed production data on BPOS should consult “Appendix - Transition Scenarios for Trial and Undeployed Customers” first.

Transition Roles and Responsibilities

Microsoft Responsibilities

· Inform the technical and administration contacts (as listed in your BPOS tenant) of the transition

· Work with you to schedule a transition date

· Provide you with information and guidance about the transition

· Prevent any disruption to email flow during transition

· Migrate any and all customer data as required for a full transition

Your Responsibilities

· Be responsive to Microsoft requests to schedule a transition date

· Update end-user computer software to meet the system requirements

· Configure end-user computer software if required

· Re-configure end-user Active Sync devices

· Inform and train your end-users as needed

· Optional: deploy an on-premise Active Directory Federation Services server if you choose to implement ADFS-based single sign-on.

· Optional: deploy an on-premise Exchange Server 2010 CAS role if you have a hybrid on-premise/cloud Exchange deployment and want to share free/busy and other information across servers 

Availability and Timeline Overview

Microsoft understands that you need the flexibility to determine when your organization will enable significant updates to the online services you purchase from Microsoft. You will have up to twelve (12) months, beginning several months after the Office 365 launch, to transition to the new service.

The following table provides a high-level timeline of key milestones for Office 365.

What

Availability Date

Comments

Beta of next major service update

Spring 2011

For existing customers, the Beta is only intended as a preview: you will not be able to merge your beta tenant with your production service.

Office 365 launch

2011

The final Office 365 launch date has not been announced at this time.

Exchange Online Mailbox Pilot Available

After Office 365 launch

Existing customers can enable a small group of users with the features and functions of Office 365.

Transitions Availability Begins

Roughly four months after Office 365 launch

This date represents the period when Microsoft will be able to transition most BPOS customers. Microsoft will contact you 60 to 90 days prior to a proposed transition date. You can accept the date or request a new one.

Transition Availability Ends

Transition Availability + 12 months

You must transition by this date – i.e. 12 months after Transition Availability begins and about 16 months after Office 365 launch).

BPOS to Office 365 Trainings for Partners

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https://training.partner.microsoft.com/learning/app/management/LMS_ActDetails.aspx?UserMode=0&ActivityId=737036

BPOS to Office365 Transition Training for Partners

Microsoft® Office 365 is an evolution of BPOS and combines the familiar functionality of the Office desktop suite with cloud...of cloud productivity to businesses of all sizes...your customers with the transition from BPOS to Office365 by participating...

https://training.partner.microsoft.com/learning/app/management/LMS_ActDetails.aspx?UserMode=0&ActivityId=744603 - 1 KB