Are *.pyd's universal?

[Lawrence D'Oliveiro]

In message <mailman.2297.1256863331.2807.python-list at python.org>, Christian 
Heimes wrote:

> Lawrence D'Oliveiro schrieb:
>
>> In message <mailman.2268.1256841007.2807.python-list at python.org>,
>> Christian Heimes wrote:
>> 
>>> On Linux and several other Unices the suffix is .so and not .pyd.
>> 
>> Why is that? Or conversely, why isn't it .dll under Windows?
> 
> On Windows it used to be .dll, too.
> The suffix was changed to avoid issues with other dlls and name clashes.

What clashes? How come other OSes don't seem prone to the same problems?