Rael Dornfest, the CTO at O’Reilly, has a pretty good writeup on Ruby on Rails and Ajax that you should probably look at if you’re (still) sceptical about switching from you usual PHP approach to web development or other frameworks like Struts. Many others including OSS’s own Bruce Perens, have claimed RoR to be the productivity boost the web needed, so even if you aren’t considering moving, make sure you have a look at it.