Microsoft’s announcement in today’s TechEd 2011 keynote, Windows Phone 7.5 aka Mango’s Enterprise features are trying to replace RIM Blackberry, the Enterprise Behemoth, with “Only on WP” features.

Microsoft had announced a lot new enterprise/business features for the upcoming Windows Phone 7.5 update called “Mango”, coming this summer, in TechEd 2011 keynote.

Windows Phone 7.5 called “Mango” will include below enterprise/business features:

• Pinnable email folders: Pin a folder to the start screen for quick access. This could be an email folder for a specific project, from a specific group or person (like your boss), or an RSS feed you’ve set up in Outlook.
• Conversation view in email: Emails in your inbox are organized by conversation, bringing replies to a thread into a consolidated view so it’s faster and easier to stay on top of the conversation.
• Server search: Search your email server (e.g. Exchange Server) for older emails no longer stored on yourphone, giving you ready access to all of your mail.
• Lync: Lync Mobile brings the Lync experience to Windows Phone customers by delivering Unified Communications capabilities, including instant messaging and the ability to see the presence of your co-workers. The Lync app will be a free download from Windows Phone Marketplace and will be enabled with support from your business organization.
• Security: Complex (alpha-numeric) password support
• Rights management: Information Rights Management support for protecting e-mails and Office documents
• Wireless improvements: Support for access to hidden corporate Wi-Fi networks

Lync client. Lync Mobile will provide the Lync communications experience on Windows Phone, with instant messaging and presence capabilities, and integration with hosted (Office 365) and on premises versions of the Lync server solution. The Lync app will be a free download from the Windows Phone Marketplace, according to Microsoft. (So it's not really part of Mango, per se.)

Office 365 integration. Mango will include deep integration with Office 365, which provides low-cost, hosted versions of Exchange, SharePoint, and Lync to individuals and customers of all sizes. This will include an Office 365 account type and Office 365 quick setup link in the Office hub.

Read more here from Paul Thurrots Paul Thurrot's blog

See in action more about the Windows Phone 7.5 aka “Mango” update in below video (video by winrumors);