Ajaxian is probably the stupidest name ever - course I think ajax is a stupid name soo... these geeks and their obsession with cleanliness...ajax, soap...
The point of this is the "ajax summit" - where a select (and I mean select) view were invited to talk about ajax in general
I was a little bit dissapointed that the php/ajax contribution to the summit was "Thomas Lackner of Sajax fame"
Now not to knock tomas, but Sajax is a multi-language library and the php implementation - well let's just say for php it is not a library or even a class - it's a single script that doesn't even do complex datatypes - e.g. objects/arrays, just straight data
Now granted - if you're using a couple different language, sajax is probably the way to go since it seems to have a unified api for
asp, php, perl, coldfusion, ruby, python, lua and io but if he was invited to represent PHP and Ajax I feel it was a poor choice
Now why he was invited and not Jpspan guru Harry Fuecks is beyond me, since jpspan is a more complete php implementation (although I think harry's been programming in java too long, I'm of the opinion itty classes are evil in php since require_once is heavier on processing/server load than anything else)
Anyway, if you're thinking of using ajax with php I'd recommend the jpspan route from personal experience - and take a look at Josh's blog for his latest tutorials/opinions on the subject of php and ajax web applications
Oh, and I found a nifty article on form usability and xmlhttprequest at baekdal.com