Prompted by comments to this question on English Learners (about "That's you done"), I've been searching Google Books for similar constructions of the general form that's [pro]noun adjective (for this context, I classify past-tense verb forms such as done, fucked, finished as adjectives).
What I seem to be finding is that using "That's" in this way (not referencing anything in particular, just "whatever came before/caused the current situation") is a relatively recent phenomenon.
I'm also getting the impression it's more common in BrE than Ame. So by implication, if the boss says to his secretary...
"Just get those letters off in the post, and that's you done for the day."
...I should assume the boss is probably British, rather than American.
Would my assumption be right? Can anyone shed more light on the usage? Is it the same as...
"Here's me doing all the work while you just sit around waiting to be fed."
(said by, for example, hard-pressed mother to idle teenage offspring)