When the application is minimized, it is still running, just not at a truly active state. Therefore, a little bit of memory is being used. Unless the application has been closed, you will see a little bit of CPU being used.
Thanks Tracy. I understand the memory usage but CPU is indicative of some sort of regular active interrogation going on (but not logged). I just don't see this behaviour with the other software tools I actively use (SAS 9.2, ArcGIS 10). Again, it isn't a huge deal -- just enough to make me curious as to what Tableau is doing (or trying to do) when minimized. Thanks for taking the time to answer.