Sadly, this is not an April Fool's joke. The W3C has chartered an XML Binary Characterization Working Group to "analyze and develop use cases and measurements for alternate encodings of XML. Its goal is to determine if serialized binary XML transmission and formats are feasible." It's likely that only people who believe in binary XML will participate, which indicates the conclusion is foreordained. However, there are so many different conflicting goals for binary XML (streaming, file size, bandwidth, parsing time, random access, strong typing, direct binding of data to memory, memory footprint, high performance in CPU limited environments like cell phones, etc.) from the players in this space that it's possible the working group won't be able to reach consensus. However there's virtually no chance that "the Working Group may determine that the benefits brought by an alternate encoding of XML may not be sufficient to justify the loss of interoperability incurred."
Andy Clark has posted version 0.9.2 of his CyberNeko Tools HTML Parser for the Xerces Native Interface (NekoXNI). CyberNeko is writen in Java. Besides the HTML parser, CyberNeko includes a DTD parser, a generic XML pull parser, a RELAX NG validator, The RELAX NG validator, pull parser, and DTD converter have also been updated. and a DTD to XML converter. This release works with the latest version of Xerces and fixes assorted other bugs.