After years of work, XQuery 1.0, XSLT 2, XPath 2 and a few related specifications are now W3C Recommendations! This is excellent news as these specifications had been "almost there" for years now. From the W3C site:
The World Wide Web Consortium has published eight new standards in the XML family for data mining, document transformation, and enterprise computing from Web services to databases. "Over 1,000 comments from developers helped ensure a resilient and implementable set of database technologies," said Jim Melton (Oracle). XSLT transforms documents into different markup or formats. XML Query can perform searches, queries and joins over collections of documents. Using XPath expressions, XSLT 2 and XQuery can operate on XML documents, XML databases, relational databases, search engines and object repositories.
Check the details at W3C.
Orbeon Forms has supported all these technologies for a long time thanks to the use of Mike Kay's Saxon XSLT and XQuery Processor and thanks to the eXist XML database, which of course supports XQuery.
Both these fantastic tools have been closely following the evolution of the specifications at W3C, which means that with Orbeon Forms, you don't have to wait: you can today already use XSLT 2.0 to transform documents and create XForms page templates, XQuery 1.0 to query XML databases, and XPath 2.0 expressions within XForms pages and XML pipelines.
Thanks to all the W3C working group members who have made this possible!