We are looking for a desktop forms technology with an easy to use (read non technical) authoring environment. When I last looked at this, some years back, it seemed that XForms would mature in to something really useful. Now there appears to be little happening with the technology (only 5 questions under the XForms tag here for instance) and not much offered in the way of tools, especially desktop based ones.
So, is XForms dead? Has something better come along?
There's a lot of software which supports XForms. I used it for a project a couple years ago, and I was impressed by the amount of work done by very little code. The W3C does not advertise their technologies to PHBs, so adoption is bound to be slow while others are pushing buzzword-compliant vendor specific solutions as panacea. There's also stigma among developers (especially those who consider themselves "hard core", it seems) against what is seen as a pointless "XML-ization" of everything in computer science. Also, the side track into HTML 5 I believe is taking the focus away from the more interesting issues on the web.
XForms has to be implemented at client-side to be publicly used. There are two projects for a free client-side implementation without plug-in nor install : Ubiquity XForms and XSLTForms (http://www.agencexml.com/xsltforms)
It's probably blasphemy to call it successor, but forms are being worked on in HTML 5.
It won't help you on desktop (yet), but that answers "what happened to XForms".