You can use [Date,System] (more info here - http://openwebstudio.com/topic/Columns_and_Values.aspx)
To format the date/time you can use the format tag as seen here - http://openwebstudio.com/topic/Formatters.aspx
EXAMPLE:
[Format,[Date,System],{0:d}] = 11/2/2012
[Format,[Date,System],{0:t}] = 7:08 PM