Ted Neward echos the conventional wisdom on CORBA - that lack of interop killed it:

For starters, Steve Vinoski was a bit miffed at the idea posited by Mark Baker that CORBA failed. Sorry, Steve, I have to say it, but I agree with Mark--CORBA never fulfilled on its intended promise of seamless middleware interoperability and integration capabilities, and certainly not over the Internet in any meaningful way. By the time CORBA began to address some of those issues--firewalls being a big one--the world had already pretty much abandoned both the "distributed object brokers" (the other being COM/DCOM) and were starting to explore HTTP as the be-all, end-all transport protocol.

Lack of interop was never really the problem - I've seen the VisualWorks CORBA broker working against a large variety of brokers, including a few that no longer exist. Ted touches on the right answer - firewalls. WS* succeeded where CORBA failed for a very, very simple reason - port 80. To get a CORBA hookup between two entities, you have to go have a discussion with the IT (and, if your outfit is big enough, IT security) guys and get them to open up a port in the firewall. Their default answer is going to be no, so this takes work. Easier to just forget the whole thing.

Now, take WS*, by contrast. Well - the SOAP posts come straight into the already open port 80, so you don't need to have that talk with IT. This makes it far, far easier for various skunkworks projects to get going before anyone notices them - by which point they might be too important to kill off.

The WS* stack is at least as complex (and, at this point, arguably more complex) than CORBA ever has been. It's no more or less interoperable between service brokers either (technology-wise). It's effectively more interoperable solely because it uses port 80.