Opera have announced SoonR, which seems to be a toolkit for doing AJAXy stuff on mobile phones (via the Opera browser, of course).

From their demos, it looks to me that AJAX on mobile is more about prettying up the interface and incremental UI improvements than it is about bringing anything revolutionary about... highlighted menu selection was kinda nice, the sliding slideshow seemed like a bit of fluff, but their Skype chat with auto refresh (which I note is "coming soon") was the only thing that grabbed me as being really neat.

Of course, the interesting thing about AJAX on the web is that it doesn't only work with a single browser; until mobile AJAX is similarly stable across many devices (which could be a lot further away thanks to the fragmentation in browser standards on phones) then it doesn't really hold the same value. To me it's a Flash competitor right now, scrapping it out with Macromedia at the edges of the mobile development ecosystem whilst WAP, XHTML and Java continue to dominate the mass market.