nodge the data is there, so it is definitely possible to write an extension for that.
As for showing a list of users who read or didn't read, I think it would only make sense on small "private" forums ? Doing this here would probably be a UI nightmare with the huge amount of users.
If you were thinking about it for larger forums, maybe you know an example website that does it ?
This could be a good candidate for one of my live extension coding.
