A paper about traps and programming stress

[bearophile]

Steven Schveighoffer:
> I feel like we will eventually need to correctly solve these types of  
> problems.  I think it could already be done using alias this for custom  
> types, but the builtins would need to be treated specially.

I am ignorant about this topic, so I keep muzzle almost shut.
See part titled "Variance" here:
http://www.codeproject.com/KB/cs/CSharp4Features.aspx
Is this feature added to C#4 related to this problem?

Bye,
bearophile