Perhaps I should elaborate. UDDI seems like a reasonable solution to the stated problem, namely how to find the endpoint URL for a web service you want to invoke. I just think the problem is the wrong one to solve.
What do I think is better? I can summarize that in three words:
Enterprise Service Bus (IBM hype, dW article, Redbook)
There's a lot of reasons for why ESB is better, but the main differentiator is this: With UDDI, you have to know the address of all the providers of a service and choose amongst them. With ESB, you just have to put your request on the right queue and it'll get fulfilled without you having to know who the providers are or which one should handle your request. The ESB does the work for you.
For a discussion of the basics of this design, see the Message Bus pattern. The complete pattern is in the book Enterprise Integration Patterns.