Some of the enhancements:
* You can now add Formulas Sum/Average/Count/Cell as well as combinations.
* Will roundtrip if not edited in previous release
* Cells will work similar to Excel. You could have a column for cost and one for quantity then take the quantity and multiply it by the cost and then sum the total.
* Can share data between tables. This means you can now link data from one table to a cell in another. Perhaps you have a table of lights with voltage and another that totals the amount of voltage in the building based on the quantity and voltage.
* When changes are made to the drawing that affect the data in the table, you will get a notification.
The new Table enhancements in AutoCAD 2006 reduces the need for maintaining external spreadsheets.