I have recently cleared the XML exam from IBM with 85%. Thought I would share my two cents on the exam and the preparation. First of all, I'd like to thank you all guys here. Your posts here reg. your experiences with the test and its preparation had been very helpful. The mock exams have been very helpful as well, esp. Shashank's mock exam(I scored only 61% in this) - thanks Shashank. I'd encourage everybody who intends to take the IBM exam to take these tests.
Coming to the test and my preparation for it, I have nearly 4 years of experience of java development and some experience of using XML with java esp. using DOM. I had prepared for this test only for 10 days. My primary preparation material was the "Essential XML Quick Reference" by Skonnard & Martin. The following are the chapters I had used this book for 1.Namespaces and XML 2.DTD 3.XPath 4.XSLT 5.SAX 6.DOM For XML Schema I went thru the "Professional XML" XML schema chapter once, but, for this my primary source was www.w3schools.com. I used the following tutorial for XLink : http://www.xml.com/pub/a/2000/09/xlink/index.html. For XSL-FO, SOAP, UDDI, WSDL I again used w3schools. I did not prepare anything for XML Security, CSS etc.
I find the Skonnard book quite thorough - I would recommend reading every line very carefully. I went thru this book for the first time carefully and later I just went thru the syntax and the examples before the exam(it just takes 3-4 hours for this exercise). The examples were very useful for the exam because there were questions which were very close to these examples. Also, I skimmed thru the DOM and SAX chapters of the "Professional XML" book primarily to understand which parser should be used in which situation. I finally took the sample test(78%) and went to the exam straight.
My impression of the exam is that it primarily tests you reg. your ability to pick up which XML technology(ies) to use in a given situation ex: SAX vs. DOM. I would recommend being thorough on DTD and Namespaces and the SAX and DOM methods. The toughest questions for me were from DTDs. The questions on XML Schema are also a bit tricky esp. about aspects of simple types and complex types and using restrictions and the elements like "all", "any", "choice" etc. So thats it guys.