[bloaf]

I'm going to point to a development case which is outside the typical "database management" case everyone here seems to be thinking about: engineering modeling software like this: http://www.aspentech.com/fullproductlisting/

This company is ostensibly doing the right thing: they have developed a large number of "single purpose" programs. They also have some applications which attempt to integrate some of their technology into single packages. The problems, however, are exactly as you describe. From an end user perspective, having the various programs send data to one another is a crap shoot. Some applications are very tightly integrated while others seem to have been developed in a vacuum. The company has even developed an entire application that tries to fix this by allowing data to be automatically exported to and imported from excel. End users could try to use the COM interface to get and send data where they want it to go, but we have to remember that the target audience is engineers, not programmers.