If you've ever used the Truncate_Only to shrink logs in SQL Server 2000/2005, it may come as a surprise to you that its use has been discontinued in SQL Server 2008.
Instead, you can use the following commands to get SQL Server to do essentially the same thing:
Alter Database %databasename% Set Recovery Simple
Alter Database %databasename% Set Recovery Full
You can then shrink the log file as normal.