While the architectural specification clearly states that you can (
http://www.w3.org/TR/2003/WD-ws-arch-20030808/[
^]) it's another question alltogether if you want to amble down that rocky road.
Here's a link where they're talking about SOA without SOAP:
http://developers.sun.com/mobility/midp/ttips/soanosoap/[
^]
The article above is java centric but the principles still a apply to any language capable of serving and/or consuming web services.
Still need help? Leave a comment then.
RESTful webservices in .NET 3.5 with WCF:
RESTful Webservices in .NET 3.5[
^]
Cheers!