As someone who migrated a Unix-only PERL application to simultaneous development in both Win32 and Unix (one source, two platforms!), I'd say PERL is pretty darn portable. It's all in how you write it. In addition, I don't even know what Unix OS this app is run on at any given time. It could be Solaris. It could be Sun. It could be Linux. Doesn't much matter to me. So long as you go through the API's provided for you by the nice people at CPAN, you NEVER have to worry about portability. Ever. Not even once.