I use SilentNotes, that can sync via WebDAV services; since I already satisfactorily use Fruux for contacts and calendar, having something usable in this way would be very appreciated.

I, too, would like to see notes added. Maybe you could put it in Tasks labeled as Notes and allow for sorting based on name. I did notice a Notes field in Task creation, but there's no way to sort by title. I created a type of notebook like this in Tasks for a list of books I've read. Really, all I would need for Notes is "Title" and "Notes" fields, and sort by "Title".

As an alternative, look into putting the Notes into the Contacts section. It would be a little weird to have to open Contacts to access my notes, but I can sort by Title.

Update:
I created a "Reading Log" address book to see what it would look like, and I like the result. I put the author's name in the usual fields, the book title in the "Nickname" field, and a description in "Notes".

The ability to take and sync notes would be tremendously helpful to me, since I'm trying to replace my paper Filofax with fruux and I kept lots of notes in there. Is there any way the VJOURNAL standard could be used for that? With support in the web app and mobile app? That would be awesome :).

Should the absence of a standard prevent you from considering this feature?

iOS 7 and Outlook use ActiveSync to synchronize notes. Can your Outlook plug-in be adapted to manage notes? A web interface could be layered on top, like Simplenote.

It would be only a partial implementation that only supports a subset of users, but it would be a feature that would draw some of us.