Everywhere I go, people use C# for everything.. drives me crazy.
VB.net is the ONLY language that is fully supported throughout all aspects of SQL Server.. but I guess that C# is now allowed in SSIS!
In SSIS 2005, you are limited to writing scripts in Visual Basic.NET. However, in SSIS 2008, because the VSTA environment is used, you can write scripts in C# or Visual Basic.NET.
Another advantage to VSTA is that you can now add Web references to your script. (This option is not available in SSIS 2005.) As a result, you can easily access the objects and the methods available to the Web services. VSTA also lets you add managed assemblies to your script at design time, and you can add assemblies from any folder on your computer. In general, VSTA makes it easier to reference any .NET assemblies.