Quote from jquery-dev mailing list

It’s difficult to maintain, separate concerns, have consistent development patterns, and provide re-usability of large jQuery applications with developers of mixed skill levels.
from jQuery-dev

Isn’t this always true for any large application, jQuery or not?

There is certainly some interesting stuff to come, from better documentation on how to solve the problem with existing techniques to John’s widget prototype that should find it’s way into jQuery UI or even jQuery core.