Each time that Oracle release a new version of the product a lot of attention is paid to the new features in that release. In fact once you’ve got an OCP then you get exams specially targetted at you, that only look at new features.
Something that gets little attention is that the feature set differences between editions also tends to change. In particular Enterprise Edition features have a habit of appearing in Standard Edition after a while. This has happened at least as follows.
Transparent Application Failover (defined as select failover) appears to work fine in 10gSE RAC and is listed as EE only in earlier versions – but then so was clustering.