I am also browsing around Adobe Labs to see other helpful resources.
I always doubt how to design AJAX framework. So I check Spray and get some concept of how to design some APIs. I look at form validation demo and its source codes. The AJAX validation is registered at the end of page, which make the code very portable. But I have different view of those attributes related validation, like minChars:20, maxChars:180 in the textarea. I believe it's better put those attributes into TEXTAREA object for easy maintenance.