CP: table column indicating in which sites the entry exists

[hldrm]

for multi-language installations, it would be very helpful to see in which (other) sites (i.e. languages) the entries also exist when viewing an entries list/table.
Currently I do not see any other option than

1. opening the entry, or
2. changing the language, i.e. showing all entries of the other language

However, it would be very helpful to find that information within the entries table itself.
Here is a quick & dirty mockup, I could imagine something like:

Of course, only someone with the respective permissions to the other site(s) should see this information.

Also, filtering by sites would then be very nice in addition.