Lock down Internet Access from Python script?

[Lawrence D'Oliveiro]

In message 
<97995159-9dfd-44e5-8c00-441c0699a9bd at f19g2000yqo.googlegroups.com>, 
roschler wrote:

> I know it's not possible to "sandbox" the Python Interpreter ...

The Google App Engine does exactly that.

How could you do it? My guess is, use some kind of virtualization (if you 
have the hardware) or paravirtualization (if you don't).