I am installing DNN 4.09.00 on a fresh development machine with SQL Server 2008 on it. I noticed something when navigating through the Installation Wizard.
There is no mention of SQL Server 2008... So, on might ask themself if SQL Server 2008 is supported. The answer is of course, "Yes." But the user interface does not give any feedback to the installer that it is.
So, if there was any doubt before, let it go away. DNN supports SQL Server 2008.
,SQL Server 2008