If you have SCOM R2 you can benefit from this release right-away. This MP package (Version 6.1.7553.0) is specific to OpsMgr 2007 R2 and will not import on product versions prior to that. You can find it in the MP Catalog.
A similar update for OpsMgr 2007 SP1 will be released in the coming weeks. It will be announced on http://blogs.technet.com/momteam
- Better threshold adjustments which results in less false positives
- Updated knowledge base and display strings
- Disabled some non-actionable rules & monitors
- Extra performance counters
These updates are based on Community, Customer, and internal feedback.
See Kevin Holman's blog about SCOM agents continuously rebooting after reaching a memory threshold. This is one of the things fixed in this newly released Management Pack.