Does Restful Webservices have any service registries like the UDDI? Or can UDDI hold Restful Webservices as well?
UDDI can be used for REST services. WSDLs can be used to described HTTP web services, but frankly I feel that it's not a real match for a REST resource architecture.
At a most basic level, UDDI is simply mapping of attributes to service endpoints. So, if you're simply looking for a system that can do that, then UDDI will fit the bill.
UDDI is not popular in the wild, wide open internet, but it is used "behind the scenes" as an orchestration component.
As Darrel mentioned, DNS is another valid discovery mechanism.
My personal complaint with DNS is simply that even though DNS has all of the advantages that's mentioned in the article he cites, the downside is that DNS is such a critical part of the network fabric, it tends to not be available to developers. Typically, the network operations folks (who tend to be more notorious than even DBAs) hold infrastructure like DNS quite close. Finally, while DNS is quite capable of these tasks, in many cases the standard default configuration and deployment of DNS may need to be changed. For example, We've started serving certificates from DNS, for example, and we had to enable TCP for DNS. Again, this meant more involvement of network ops.
On top of that, while there is a lot of expertise and knowledge of DNS out in the world, knowledge and expertise of HTTP and "doing stuff" on a web server is far greater. That consequences of that simply means that when developers think about and look to some kind of solution to this problem, the first place they're going to look is likely an HTTP based solution.
So, in that sense UDDI is possibly a better solution, just in terms of being able to get it rolled out quickly with little hassle.
Of course, UDDI is a SOAP based service. That's not that big a deal, really. Not a great fit for a RESTful system, but it's not awful. Functional, if a little "impure".
As for a standard HTTP based service registry, there's nothing that I know of. It's reasonably simply to adhoc one simply with HTML, for example. The fact that UDDI hasn't taken off in the World at large isn't so much a limitation or slight against UDDI. Rather it's simply that the vision of discovering arbitrary services hasn't really come to fruition, the need simply isn't quite there. There's a lot more involved out of band with service discovery beyond location and semantics, like business relationships and such.
Internally, within the enterprise, those logistics are solved, so service discovery has value. Out in the wild, not so much.