php extensions for ppc?

[bronto]

I'm working with a new php application that has a feature for compressing a 
file.  The php code tests:

if (@function_exists('gzcompress'))

and the option in the script isn't available, so I am assuming that I do 
not have this function available to my php.

Is this an extension that I can drop in?  Or do I have to recompile php?

On a related question that I've always wondered, are .so files platform 
specific, or will any .so work with ppc?

Thanks