Give me a template. I give you a framework.

I personally would like to have

templating with caching. On the first rendering, the page is written on the disc and its filename saved in DB. On content edit, update_cache flag is set to true.
update_cache flag is set to true also when a filename that the page links to is changed.

link consistency. In content, links should be written as {CT-LINK-[ID]} and replaced with the correct links to pages during rendering.
Possible issues: how to write links in source edit mode? Write special hooks for EditArea?
How to handle linking to files? Browser based file manager is easy, but how to do it with FTP, without "re-indexing"-features in careTaker.

support for multiple mime types. HTML, text and PHP are planned content types, maybe others?

AJAX. Site and menu structures are definitely AJAX (drag-n-drop), but how about the rest? To go all the way, have a 100% AJAX app, or build the initial page server side and do subsequent calls via AJAX, until user wants to change page?
Possible issues: Usability. Should I bother with it at all? You couldn't use careTaker anyway without javaScript enabled, so is there any sense to pretend to be usability-friendly?

access levels. A multi-user environment, at least to separate content manger from the super administrator. Maybe even custom definable levels?

nice URLs only. Content should be served as /path/to/content.ext, depending on where user saved the page in the virtual file structure.
mod_rewrite is obvious, but what about IIS support? Ditch it, or offer a 404-page based alternative?

customisable template format. User can define what files make out a template. One file for the content to be inserted in, another for the editor area css classes, for example. All filenames self-definable. Maybe even template files for each mime type (text its own, html another), or multiple template files (the template to be used could be selected in page edit mode).

clean interface. The user interface should be as clean and simple as possible. Consisting of a single editor box, if possible. Additional interface elements should be hidden by default and slide in view only when needed (see design suggestions for an example).

simple administration. Installation wizard and live updates would be nice. careTaker should also be as self-configurating as possible.

I would rather not have

user defined template variables. The templates will have {CONTENT} and {MENU[menuname]}, should there be more? A user could define an arbitrary amount of blocks and then write content for them to be replaced during parsing.
Is this too customisable? careTaker is supposed to be as simple as it gets. On the other hand, this might be the only way to get dynamicly controlled template parts (think of banners, category images etc)

plugins. I don't like them. They are nothing but a feeble attempt to improve a software that does not live up to its expectations. If careTaker hasn't got it, it doesn't do it.
Loophole: plugin hooks to let developers easier modify careTaker for their needs?