There will be a mistake. A bad one. Customers will be inconvenienced, damaged, frightened, perturbed, and angry.
Say you’re sorry. Then say what happened. Then say you’re sorry again. Save the soul-searching “This has been a bad day,” stuff for your spouse — because it’s been a worse day for many of your customers.
Do not try to publicly minimize the inconvenience your company’s foul-up has caused its customers. You don’t know what it’s like for them. Also, blogs will skewer you.
Over-apologize, over-compensate, over-fix. Do you want to be Toyota?
Check out these apologies. Both help a bit, but they have flaws that could easily have been avoided. Can you see them?
Rafe
Pro PR Tips 
Amen, and amen! Mistakes happen – but so should apologies (real ones!).
Thanks for your insights – keep up the inspiring work!
It’s almost like your talking about a recent accident, that McAfee had… xD