New features

One of the paragraphs in Powell's DW tuning book was something on the lines of (and the book is not with me right now)

...features such as bitmap indexes, bitmap join indexes, index organised tables and cluster tables were introduced in previous [before 10g] versions of Oracle, they are legacy techniques and since then the query optimiser has been improved it may not be necessary to use these techniques in a new data warehouse...

The gist, if not the exact words. I am not sure that bitmap indexes have already been superseded but there is some truth in the concept that new features are introduced in each release of a database (and not just Oracle ones) and the open minded should always be prepared to experiment, measure, benchmark to see if the new is better for your circumstances than the old methods. Oh, and reading the release notes is good idea, too especially about depreciated features