MS SQL Server 208 includes several new data types, one of which the the 'date' data type which occupies 4 bytes. Most applications that need to store only the date currently use the datetime data type which uses up 8 bytes.
Also available is the 'datetime2' data type which can store date & time with much more accuracy than the 'datetime' data type.
The date and time data types included with SQL Server 2008 are:
time, date, smalldatetime, datetime, datetime2, datetimeoffset