I recently found that you can add writePermissions onto a Folder through the JSON, and it seems to work in that when I read the CanWrite prop of the Folder in the runtime, I can see it changes based on the user logged in. However, it doesn't extend to the tags within the folder... 
It was so close to being extremely useful!
Will this functionality ever make it into the product?
wasnt 8.3 gonna add in a bunch more stuff to the json settings instead of internal db?
There is no internal DB in v8.3 at all. But I think Nick is hoping for tags to inherit security settings from their folder. Distinct issue/feature.
Haha, re-reading my post it was a little obscure, but yes, inheritance of security was my request
Folder are a bit special...We put some custom properties to folder, with tag write function. (for example a string with an icon Path)
You can read and write them with script function, but they are not visibile int he designer.
Yeah, folders becoming their own "object" would definitely help here, and I hope with 8.3 and the alarm summary information, that it adds more possibilities going forward and maybe even allow more visibility with "folder" or "areas" so that we can add our own functionality on top of what's already there. Right now I just create an "Area" tag in each folder that has info in that UDT that allows me to track the display name for that area, alarm summary, default OPC path for any tags inside that folder, etc.
Right now we use the Spreadsheet Import Tool to write (custom) properties to folders in bulk, but it would be great if these were exposed in designer.