Just a pointer to two blog posts that I find worth mentioning:
1. Christo Kutrovsky from Pythian writes about some quirks he found regarding Parallel Distribution of aggregation and analytic functions. In particular the lower part of the post (which is not about the initial Interval Partitioning issue) gives a lot of food for thought how the chosen Parallel Distribution can influence the performance of operations
2. Alexander Anokhin gives some geek insights into how Oracle performs logical I/O and in particular how the "buffer is pinned count" statistics is maintained by Oracle. He even introduces another cool tool ("Digger") for performing such investigations based on DTrace.
That post quite nicely complements my "Logical I/O evolution" series.