Cumulative Update 5 contains a number of fixes for Operations Manager 2007 R2 and adds support for Red Hat 6. A number of fixes require manual steps to install. See Knowledgebase article KB 2495674. You can download Cumulative Update 5 here (948 MB).
The KB2495674 article apparently is not online yet but can be found here: http://support.microsoft.com/kb/2495674
For instructions on how to install a CU package in general (blog is written for CU4 but best practices can be followed for installation of CU5 as well) you can check this :http://blogs.technet.com/b/kevinholman/archive/2011/02/01/opsmgr-2007-r2-cu4-rollup-hotfix-ships-and-my-experience-installing-it.aspx