I've read and re-read the Iterable section in the Apex reference manual but I just don't get it.  How do you specify the SOQL query to select the records for processing?  Or do you just pass a List of objects into Database.executeBatch(), and does that List become the scope in the example on page 253?

And finally - if Iterable is subject to the standard governor limit on SOQL retrieved records, why would you use it?  I can't see the benefit of using it vs. a standard Apex class if the limits are the same.

Thanks
David