emgrid 10.2.0.3 is not the second patchset of 10gR2, it is Oracle Enterprise Manager Grid Control Release 3.
Well, it is still called a patch set and must be applied to 10.2.0.1 or 10.2.0.2.
But it is a new release !
You can download the soft and the doc on otn
Out of the new features, you have a Linux pack for your Unbreakable Linux, Management pack for Siebel and Oracle Content Database, and also Linux Server Administration to manage your Linux (RHEL4 and SuSE9).