The official Cisco certified version of Exchange 2010 for use with Unity is 2010 RTM RU3, as of today (10-27-2010).
Exchange 2010 RTM RU4, Exchange 2010 SP1 and Exchange 2010 SP1 RU1 have all come out since Exchange 2010 RTM RU3.
Many enterprises have already upgraded to Exchange 2010 SP1 and SP1 RU1.
Cisco is working on getting Exchange 2010 SP1 certified but it hasn’t been yet with no ETA.
Updates on Cisco Unity support will most likely end up
here. It contains the most up to date instructions on how to update the Unity servers to interop with Exchange 2010.
On a good note, a new version of the Exchange 2007/2010 MAPI CDO was posted on Microsoft's website
here a few days ago, which seems to fix the issues noted
here on Cisco's website and noted
here on Microsoft's website.
Known gotchas with Exchange 2010 SP1:
By default, the Unity 7.0(2) ES train patches try to use old Exchange 2010 RTM Powershell commands to create the Unity mailboxes if you are trying to partner with the Exchange 2010 server in a brand new Unity install. The workaround is to partner with an Exchange 2003 server during this process or manually create the mailboxes before applying the Unity patch.
If the Unity service mailboxes already live in the Exchange 2003 environment, and/or Unity is already partnered with an Exchange 2003 server, it can modify the accounts it needs, assuming you’ve given those accounts the right permissions.
If they are using Unity 7.0(2) ES36 in a fail-over environment, you need a database fix-up utility from Cisco TAC to prevent failed fail-over of Unity servers, called CiscoUnity_7.02_Patch11e.exe. Telltale sign of the issue:
0x80040e37 - Failed to verify SQL Configuration Table
Fun times on the bleeding edge, right?
Update: Cisco has updated their site and has support for
Unity 5,
Unity 7, and and
Unity 8 with Exchange 2010 SP1.