Are *.pyd's universal?

[Lawrence D'Oliveiro]

In message <6e603d9c-2be0-449c-9c3c-
bab49e09e8fc at 13g2000prl.googlegroups.com>, Carl Banks wrote:

> It's not Python that's the issue.  The issue is that if you have a
> module with a .dll extension, other programs could accidentally try to
> load that module instead of the intended dll, if the module is in the
> current directory or system path.  Modules will sometimes find
> themselves on the path in Windows, so the fact that Windows performs a
> library search on the path is quite significant.

Why is it only Windows is prone to this problem?