Jeff:
My concern with with the original circuit is that there is no way of differentiating between a press and a release if the key bounces on either action. I can't recall if there is any simple means of checking the IRQ line without actually triggering an interrupt.

The program could keep track ...

I don't think that the circuit will work the the way you think its will. Unless you are expecting a very long interrupt response time and you need to latch the event, the circuit is pretty much redundant.

The keypress will be latched and the interrupt asserted as you expect, however, the response ...