Like Saurav Sarkar, I too feel that these topics are not very closely related.
Web Services are one of the xml based standards for making reusable services.The main transport was HTTP protocol so the
word 'Web' has been associated with it , though now it supports many other transports.
Servlets are mainly for delegating the flow further for services invocation while the actual service would be somewhere , but not as part of the servlet code.That may be a web service ,
EJB or something else.
Another work of the servlet would be to direct the flow to the view with all the required data for generation of the final HTML response.
[ July 29, 2007: Message edited by: Rahul Bhattacharjee ]