zIWT now saves an original copy of your post in addition to the scrubbed version, if your original is not the same as the scrubbed version. So edits will still have what you typed in originally.
The upshot of this is that I can now do some really nifty things, like Ben's tag protocols and the like. The only downside is that the code that does the link scrubbing is an external python module, which means I need to restart Zope to make changes (doh!) unless I can figure out how to reload an external module within Zope.