Houston, we have a problem
Seriously, the comment of Dare's that Mark cites is complete BS. The whole point of Web services is supposed to be that you should not need to, know the hardware platform, operating system or programming language of the system with which you interact. Granted, the same characteristic applies to REST as manifested with HTTP.
This whole discussion of "when to use SOAP vs POX/HTTP cum REST" is simply inane. It's about as silly as the "which is better: Java vs C++ vs C vs Smalltalk vs Ruby vs Python vs Perl vs tcl vs ..." debates.