I'm really really excited about new 11.2 external tables preprocessor feature. Oracle documentation show examples based on compressed files and how to load uncompress them on a fly and load them to oracle.
Although that is interesting use of external tables preprocessor, I think what is more interesting is the fact that it can be used outside normal ETL and can be great tool for DBAs who run scripts in unix, now they can execute the scripts from oracle environment (e.g. oracle apex) and read the results of the script very easy way using select * from ... (until now I was using JAVA for executing unix scripts from Oracle environment, this is easier way for sure)
I posted few very simple samples on my blog http://jiri.wordpress.com/2010/01/19/no-more-unix-scripts-in-11-2/
I agree the external tables preprocessor is a great feature.
BUT, I have a problem when I use it with Oracle APEX 4.1.
It gives ORA-29913: error in executing ODCIEXTTABLEFETCH callout