Krishna, Yes. You can use SOAP with other protocols. For example, you can use SOAP over JMS in IBM WebSphere server. However, at this point, the basic profile only supports SOAP over http. So, if your application uses SOAP over (say) JMS, it won't be interoperable. In other words, you can use other protocols for internal communication between your applictaions but for external exposure, you should always use soap over http to remain interoperable.
HTTP is a transport-level protocols and SOAP is a messaging-layer (communication) protocol. SOAP can be used in combination with a variety of transport protocols - including SMTP, JMS, and other protocols in addition to HTTP - and does not depend on any particular network protocol. Although HTTP is a widely used protocol for SOAP, SOAP toolkit vendors have also started providing support for other protocols, like SMTP. SOAP messages may travel across several different transport-layer protocols before they reach their ultimate destination.