According to this article, Oracle will power 'Bebo" a MySpace-like social networking application.  Bebo must be highly scalable and able to minimize disk I/O by accessing related information in a single disk read.

"The IOT option allows users to store indexes and tables and associated rows in the same place, reducing the amount of effort necessary to "fetch" information, according to Birch.

Before Bebo.com started using IOT, records for individual site users were stored in different places and on different discs, and retrieving the information required a lot of physical I/O. That dilemma led Bebo.com to IOT.

"We adopted IOT, and we converted our tables to it. You can actually convert tables on the fly and it doesn't require downtime," Birch said. "We converted a lot of tables and saw huge gains in terms of the amount of discs we needed."

Things are currently running efficiently at Bebo.com, but Birch says that -- going forward -- anything Oracle can do to help improve database performance would be welcomed with open arms."

Contrary to the "pure" relational model which says that physical disk organization should not matter, real-world DBA's frequently reorganize tables to maximize I/O efficiency.  IOT's and Oracle Cluster tables allow for related rows to be stored adjacent to one another on a single disk block, dramatically reducing disk I/O overhead.