People (namely one person) do(es) this in my home game all the time, and nobody seems to care. I consider myself to be one (of two) of the most serious players there, and it doesn't bother me; I'm usually not the one pushing all in against him, and when I am, I just stare at the community cards so no one can get a read. To me, announcing what he has is no different than flipping his cards, and in my game we allow sharing our hole cards with players out of the hand anyway. Its all a matter of personal preference, do whatever you and your players agree on.

Steve