In the past year or so, I've seen more and more RESTful services offered. I've also seen the connectivity emphasis in development systems that I like, such as Ruby on Rails, shift from XML Web services to RESTful services.
In the particular case of Alpha Five V10, calling a RESTful service boils down to writing a call to an HTTP function: the generic HTTP_FETCH() function, or specialized HTTP_GET(), HTTP_POST(), HTTP_PUT(), and HTTP_DELETE() functions. Building the URI and parameter strings is very straightforward using Alpha's Xbasic language, which has a strong set of string functions. Parsing the responses is also straightforward, even when they're in XML form. I typically package all of that as an Xbasic function.
None of these things amounts to a magic bullet, but it does all hang together nicely. And I've managed to produce a fairly sophisticated application in a short amount of time.
If you'd like more information at a concrete step-by-step how-to level, a white paper of mine on using RESTful interfaces to create AJAX mashups with Alpha Five V10 is available for downloading.