SD Times carries an article by Larry O'Brien on REST vs. SOAP. As I already blogged in the past, I fully agree with his position. We cannot say that WS-* is dead... only because it never came alive. REST, on the other hand, is doing quite well and I prefer using it whenever possible.

Now, looking at the biggest web players, it is interesting to see which APIs they promote. As an example, I've checked search APIs, that is how you can create a custom search based on the most relevant search engines:

• Google used to have a SOAP-based search API I used in the past. As of last December, they killed it. Now the only official alternative you have it to use they JavaScript/AJAX-based API. This is good for a web site, but not for a stand alone Windows application that needs to perform a search. Notice that for other APIs Google uses REST, as well. They seem undecided, but are moving away from SOAP.
  
• Yahoo has a REST-based API. Totally open and very easy to use both from web sites and standalone applications. They actually have REST-based APIs for most of their services. No SOAP.
  
• Microsoft has a SOAP-based search API. The site provides almost no information and the mixed references to MSN-search and Windows Live Search are confusing. But the service seems to be very open (I've not tested it). Microsoft was and still is a big fan on SOAP, but RESt is starting to creep there as well, and they are also actively moving into the AJAX field.

What about Delphi? You can directly interact with the Yahoo and Microsoft services, and indirectly create web pages that use the Google one. I guess a "long article" or "short book" on this issue would be an interesting tutorial, even though there are many sources covering how to use similar web services...