[civild]

The term "ETL" itself is often used in place of "Data Integration" which is much larger, particularly when it comes to data warehouse design. The wiki article is a good drop off point: http://en.wikipedia.org/wiki/Data_integration

It may be difficult to understand how this is an industry coming from a web development/startup angle (big supposition there) but there are literally thousands of companies with lots of databases varying in age, size and complexity that need integrating, and plenty of companies competing for that work as either implementors or software providers. A perl script might do the job but most products focus on performance, reuse, ease of maintenance and compatability across many different database/file types.