I'm not sure EAI and Web services are mutually exclusive. EAI is a very broad term that describes the sharing of information, application services and processes between systems existing within the same enterprise. Web services fall in the domain of EAI as both an enabling technology and set of standards (e.g., UDDI, WSDL, SOAP). I discussed this in more detail when responding to a previous question similar to this one. [Editor's note: See David's previous answers here.]
Indeed, Web services allow EAI architects to integrate many back-end systems through the creation of loosely coupled composite applications. Distributed objects perform a similar trick (albeit they are more tightly coupled). Web services is a technology and set of standards existing in the application service-oriented approach to EAI, which is only one of many approaches. So, I would note argue that Web services are a preferred methodology over traditional EAI, I would argue that it may take EAI and B2B application integration to the next level.
This was first published in January 2002