I still find myself wondering, occasionally, what the hoopla around data warehousing is. Virtually anybody who works for a company that has been in business long enough to define the word 'mainframe' already HAS a data warehouse. By that I mean data stored away in different formats among different systems that are typically incompatible. Typically, the real problem with these 'warehouses' is not the storage but the picking of data.
The trend seems to be to create yet another warehouse, where data is regularly collected from one warehouse and stored in another (albeit in a fashion more optimized for analytics). This is a financial boon for those who run the warehouse business, but is the value really gained simply by moving the data? Why not a software platform that is vendor agnostic, capable of stitching together data from the various existing systems, using meta data to arrive at consistencies in definitions, and making that data available for reporting without requiring that it be physically moved?
Buy the ticket, take the ride. -- Hunter S. Thompson