"Why the <insert your favourite expletive here> doesn't SSIS support C# for the script task and script component?"
I've heard the above complaint, in various different ways, many many times over the past 18 months since SQL Server 2005 was released. Its a valid complaint to which there is a valid answer (which I'm not going to go into right now). Regardless, with the arrival of katmai the complaint won't be heard any more. The script task and the script component now feature support for C#.
This has been made possible by replacing Visual Studio for Applications (VSA) (which is what the script task and script component used to use) with Visual Studio Tools for Applications (VSTA). VSTA is a much richer environment for extending applications and it has that all important support for C#.
I saw a neat demo a few months ago of what is capable using VSTA within SSIS. You can now add web references to your script tasks and components which means that it is now very easy to call web services from within the pipeline. It was possible in SQL Server 2005 but you had to hand crank the code yourself or use wsdl.exe to generate it. Now, its as simple as adding a reference. I hope to have a demo to show you shortly. UPDATE 2008-03-04, A demo video of this is now available at Consuming web services in SSIS 2008.
UPDATE: Another reason why the use of VSTA is such a good thing. You no longer have to go through this rigmarole in order to use other assemblies. GACing them will be sufficient.
-Jamie
P.S. I know Simon has mentioned this already but I already had this blog entry drafted so I'm posting it anyway :)
Further reading:
An overview of VSTA's capabilities : http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=908415&SiteID=1
Select Variables dialog in katmai : http://blogs.msdn.com/mattm/archive/2007/06/06/select-variables-dialog.aspx