This week's giveaways are in the MongoDB and Jobs Discussion forums. We're giving away four copies of Mongo DB Applied Patterns and 4 resume reviews from Five Year Itch and have the authors/reps on-line! See this thread and this one for details.
It wasn't ever used much (aside from inside large corporations), and there hasn't been much talk about it for years, even though the standard and its implementations are still being developed. To what end is not clear to me - the market in SOAP WS UDDI was meant to enable never happened, and at this time -with SOAP being much less in favor than it used to be- I don't see that it ever will. IMO, spending time on UDDI at this point is wasted.
Somewhat longer answer:
Even though UDDI in itself isn't used anymore the concepts behind it are still very relevant. The goal of UDDI has always been to form a sort of phonebook / central registry where you can look up services and from there start interacting with the service. This never really took off, but what you do see more and more is a more pragmatic kind of registry. All the large SOA suite vendors offer their own registry, where consumers can find the details of a service and providers can register their services.
This, however, usually uses a more simple approach through a REST interface or even a basic web interface since more often then not, this kind of information is used for human consumption.