Judging by the semantic blogs and lists, OWL-S, a vocabulary for describing web services in RDF, seems to be the hot schema of the moment. So, with a view to producing some OWL-S documents for the SchemaWeb web services, I have downloaded the example files and have started reading up the specs starting with Semantic Markup for Web Services.

Firstly congrats to the team for producing high quality documentation. These specs are concise and very readable.

The story I've gleaned so far is that in OWL-S a 'service' consists of three things.
1. A profile that describes what the service does. A high level description that provides a publication and discovery framework for clients and service providers. This is the UDDI bit.
2. A process model that describes how the service works in terms of IOPEs (input, output, preconditions and effects). This is an abstract description of a service.
3. A grounding which describes how to use and physically interact with a service. This covers protocols, message formats, URLs and ports etc. Similar to the 'concrete' bits of WSDL (<binding/> and <service/> elements). In fact WSDL and OWL-S are complementary and are used together to define SOAP web services in OWL-S. So don't throw away your wisdels yet!

Some first impressions and comments.
OWL-S combines the functionality of UDDI and WSDL in one model. +1.
OWL-S allows for reverse directories where clients do the advertising and service providers do the discovering; This is not possible with UDDI.
OWL-S allows 'complex' long running processes 'composed' of many web service calls to be described. This is an obvious advantage over WSDL which has a more highly grained focus and describes only individual web methods. This ability to create and advertise high level services will be good for clients and discovery and also allow third parties to aggregate diverse services and add value.
This is a complex specification. If you have slagged off WSDL in the past as too hard then you might change your mind after looking at OWL-S. And roll on tool support because I don't think there's going to be much hand coding of this baby!