What with the hype of Web 2.0 I thought I'd make a bold, easy to prove wrong prediction about what will be talked about as Web Services 2.0, namely semantic Web Services.
Semantic Web Services, for instance the WSDL-S submission to W3C aim to describe the web in terms of a series of ontologies ideally in a standardised ontology language these can then be mapped, potentially automatically from one form to another to create a richly described environment that is not limited, or based on, a basic WSDL description. The ontology could include all manner of details, restrictions and rich information about itself that would help in the discovery and implementation processes.
This of course is the theory. The problem is that the tools are currently pretty basic, and are based around an assumption that I'm not sure applies that often in the enterprise, namely that I don't really know what I'm calling. While having a single enterprise data model is always a non-starter, its not right to then assume that all information can be defined in any old way and a rich ontology is required to help drive the mapping process. Most integration projects have got by fine with what they have at the moment and the amount of definition will really have to justify itself to get used.
Semantic Web Services might be the killer app for Web Services 2.0 and create a rich environment by which invocations are automatically mapped using sexy mathematical and semantic technologies.
Or of course you might still want to make sure that your PO is mapped to the right field on the invoice and do that via a simple phone call. And this is the challenge for me on how Semantic Web Services will fly in the main. Some of the technology will definitely be useful (they talk about pre-conditions and effects, but only in terms of the data not functional verification) but given that mappings are irregular elements, are are liable to stay so while companies want to know who they are dealing with, will semantics really give a real benefit for the definite increase in complexity that they bring.
If Web Services 2.0 really is about the Semantic Web then its going to get a whole lot more scary out there. The joy of Web Services 1.0 was that SOAP meant SIMPLE, with WS-* its got more complex, and with Semantics its going to get very complex indeed.