They have some AJAX right now in CVS, and they are further extending it. "To javascript or not to javascript" was apparently a contentious issue for awhile. I think they settled on using the Prototype JS framework. I don't know when they are planning to release it.
WebERP has a nice feature set and a solid feel. There is an active development and user community. And they have real accountants on the core team. A comment on another thread suggested tackling the tax form issue by setting up report templates that output onto preprinted forms. There may already be some usable templates floating around for a starting point.