I'm fiddling around with nullable types in Whidbey and just discovered a DataRow property that is not even new, but I had never known was there (or maybe it flew by me once but it didn't stick in my brain):

DataRow.IsNull("mycolumnname")

Obviously invaluable when dealing with value types.

I guess in the 3 years I have been doing .NET, I just hadn't needed it. My main production app has a sql server database that started out being used by VB5 then VB6, so I was used to not creating DateTime columns as nullable, or dealing with nulls directly in the stored procedures. Well, I'll be!