the practicality of the new.
of all the myriad responses to jjg's fine ajax essay, the most intriguing ones are those that raise a question i've pondered myself: why now? as jesse points out in the essay, none of the technologies bundled up into the term "ajax" are new — some are actually several years old and have been steadily gaining usage in other contexts. and certainly the idea of stateless client applications has been around forever.
so why does it feel relevant now? why name it now? what's changed? a few people point to the rise of xmlhttprequest, a little-used-until-recently aspect of the latest-n-greatest browsers i first learned about when i saw it working its magic on flickr's photo pages. and some other folks have suggested it's an outgrowth of the rise of web standards and a grateful world finally being allowed to abandon support for netscape 4- browsers. but there's more to it than just technology. really, technology is the least interesting thing about it. as with so many things technological, what matters is not that it works; what matters is that people believe that it works. and to get to that, people need to see somebody else use it first.
expectation and assurance are a big deal in this context. google's use of the ajax approach lends an imprimatur to it that goes far beyond what any individual — even a really loud one — will ever be able to convince somebody not as technically inclined to believe. it doesn't matter to managers that it makes for cool web apps; it matters that it's not going to break, that their ass isn't going to be on the line for pushing something new, that they're going to be able to prove the value of the technology in some manifest way. most people in this world, sadly or no, me-too it more often than not, and that means they need someone else to do it first .
in this case, google, darling of wall street, leads, and we all benefit. or to put a new twist on an old saying, nobody ever got fired for copying google.
 in my line of business, this is what's known as "market opportunity."