Lync Server 2010 can be integrated with Exchange 2010 SP1, so that Exchange Outlook Web App can also act as a Lync web client. Once integrated, users will automatically log into Lync when they log into OWA. The OWA interface changes to include the following new features:

• Sign In and Sign Out – Users can sign in or sign out of instant messaging from OWA. Once signed in, the user will automatically sign into IM every time they sign into OWA.
• Presence – User presence information is available for Lync users, showing a colored chiclet indicating their availability.
• Contact List – The user’s Lync IM contact list is made available in the OWA folder pane. Users can be added and removed, and contact groups can be managed directly from OWA.
• Instant Messaging – Lync users can chat with other Lync users using instant messaging directly from OWA.
• Right-Click Functionality – Right-click menus and actions are updated to include new Lync features. For example, right-click an email address to chat with the user or add them to an IM contact list.

All of these new OWA features can be seen in the screenshot below:

An instant messaging chat session can be started from OWA by double-clicking a contact in the Contact List or right-clicking an email address and choosing Chat.

1. vcredit_x64.exe
2. UcmaRedist.msi
3. UcmaRedist.msp
4. UcmaRedist-R2.msp, if your CAS is running on Windows Server 2008 R2
5. CWAOWASSP.msi
6. CWAOWASSP.msp
7. dotnetfx35setup.exe, if the .NET Framework 3.5 is not installed on Windows Server 2008. For Windows Server 2008 R2, install the .NET Framework 3.5.1 feature from Server Manager.

$cert = (Get-ExchangeCertificate | Where {$_.Services -ilike “*IIS*}).Thumbprint

Get-OWAVirtualDirectory | Set-OWAVirtualDirectory -InstantMessagingType OCS -InstantMessagingEnabled:$true -InstantMessagingCertificateThumbprint $cert -InstantMessagingServerName pool.domain.com

Be sure to change the InstantMessagingServerName value in the command above to the FQDN of your Lync Server pool.

• Open the existing topology.
• Expand your Lync Server 2010 (RC) > your sitename.
• Right-click Trusted application servers and select New Trusted Application Pool.
• Enter your CAS server or CAS array’s FQDN in the Pool FQDN field, select Single Computer Pool and click Next.
• Select the Front End Pool for the Trusted Application Pool.
• Click Finish.
• Right-click the new Trusted Application Server and select Edit Properties.
• Clear the checkbox for Enable replication of configuration data to this pool and click OK.

• Publish the new topology. Note: Ignore the warning "The following machines from the topology you are publishing were not found in Active Directory and will result in errors during Enable-CsTopology as it tries to prepare Active Directory entries for the toplogy machines. ," if you used the FDQN of your CAS Array.

New-CsTrustedApplication -ApplicationID ExchangeOutlookWebApp -TrustedApplicationPoolFqdn cas.domain.com -Port 9999

Enable-CsTopology

Be sure to change the TrustedApplicationPoolFqdn value in the command above to the FQDN of your CAS server or CAS array. The Port value can be any unused TCP port.

Source: http://www.expta.com/2010/09/how-to-integrate-lync-server-2010-with.html