thats just speculation, even though AT guesses the correct units

I talked about this subject in my presentations at Connection, HP World and CMG 2003-04.

depending on the version of BOL you have, follow the chain

S2K BOL: Administering SQL Server > Managing Servers > Setting Configuration Options > cost threshold for parallelism Option

The cost refers to an estimated elapsed time in seconds required to execute the serial plan on a specific hardware configuration.

SQL 2005

Administering the Database Engine > Managing Servers > Setting Server Configuration Options >

or search: cost threshold for parallelism Option

Steve Sadler actually found this in the documentation for me, as I only heard it without hard document