When I use another object in the .net-Framework in C# I can save a lot of typing by using the using directive.
using FooCompany.Bar.Qux.Assembly.With.Ridicul
Thanks everybody for your input. I've marked Richard Berg's contribution as an answer, because it most closely resembles what I'm looking for.
All your answers brought me on the track that seems most promising: In his blog post Keith Dahlby proposes a Get-Type commandlet that allows easy consutruction of types for generic methods.
I think there is no reason against exetending this to also search through a predefined path of assemblies for a type.
Disclaimer: I haven't built that -- yet ...
Here is how one could use it:
$path = (System.Collections.Generic, FooCompany.Bar.Qux.Assembly.With.Ridiculous.Long.Namespace.I.Really.Mean.It)
$type = get-type -Path $path List Thingamabob
$obj = new-object $type
$obj.GetType()
This would result in a nice generic List of Thingamabob. Of course I'd wrap up everthing sans the path definition in just another utility function. The extended get-type would include a step to resolve any given type agains the path.