There I was the other day slowly building up a new bts project in VS.NET.
You know the way it goes, add some schemas, maybe maps and before long you have a couple of helper assemblies and maybe a custom pipeline component or 2.
The problem is that the C# Assemblies don't automatically get added to your BTS Application in the BTS Admin console.
Usually I'll drag down one of my mammoth powershell 'build all' scripts from a previous project and customise this for the current project. 2 days later I usually stick my head up to see which day it is, and typically as we developers do, build a ferrari for something that a skateboard would do.
So simply put - add the following line to your Post Build Events section on your project in VS.NET.
btstask AddResource -ApplicationName:"Micks Demo App" -Type:System.BizTalk:Assembly -Overwrite -Options:GacOnInstall,GacOnAdd -Source:"$(TargetPath)" -Destination:"%BTAD_InstallDir%\$(TargetFileName)"
Enjoy only a few more sleeps till Santa!