The Exchange 2007 for OpsMgr07 has been release http://www.microsoft.com/downloads/details.aspx?FamilyID=1a83e112-8677-4e03-83c3-f1b7ebfc3a4b&DisplayLang=en
This MP has a dependency on the Backward compatibility MP 6.0.5000.16 (or above) also released today (http://www.microsoft.com/downloads/details.aspx?FamilyID=655cdd06-861e-4342-99b2-8a81e09f6546&DisplayLang=en )
The Exch2007ReleaseNotes.htm extracted by the msi references the release note for the MP online via the link http://go.microsoft.com/fwlink/?LinkId=96219 . The online release notes should be available shortly (not at the time of writing this).
From the download page
The Microsoft Exchange Server 2007 management pack is designed to be used for monitoring Exchange 2007 events, collecting Exchange component-specific performance counters in one central location, and for raising alerts for operator intervention as necessary. By detecting, sending alerts, and automatically responding to critical events, this management pack helps indicate, correct, and prevent possible service outages or configuration problems, allowing you to proactively manage Exchange servers and identify issues before they become critical. The management pack monitors and provides alerts for automatic notification of events indicating service outages, performance degradation, health monitoring, and centralized management. This MP requires the Backward Compatibility Version 6.0.5000.16 (or above). Management Pack Release History: -Initial Release 10/9/2007: Version 6.0.5000.0