How do people use XQuery and/or XPath 2.0 from Delphi? I've got MSXML v6.0 working from Delphi, so any sufficiently documented COM-implementation will work. What's your favorite?
My Favourite: I've always found that importing MSXML provides excellent support for all the XPath queries I've ever needed it for.
Close second: I'm not aware of any native delphi libraries that can match MSXML's depth of features however OmniXML provides great support for basic XPath queries and if you're not using expressions, for example, then it's a pretty good alternative.
Sadly, I do not think that there are currently any native Delphi XML Libraries that fully support XPath 2.0.
I love OmniXML. It has a lot of supporting code and classes that extend its primary usage. You may also want to look at SimpleStorage that simplifies work with XML a lot.
You can use the fast and opensource libxml2 library. There is a Sourceforge Project for free Delphi bindings.