Well. It was bound to happen sooner or later.
And it happened today!
I lost ALL of my contacts.
Because I sync my contacts between my Mac, my phone and my .Mac account if I accidentally delete a contact in any of these it is deleted across the board.
Somehow ALL my contacts got deleted in my Mac address book and so this deleted my contacts elsewhere.
There is one consolation. I was able to print out a hard copy of my .Mac version of my contacts [Which is about a month out of date] just before my major sync/deletion occurred.
So now it is a data entry task to move the 100 or so contacts back into my Mac address book and then synced to my phone and .Mac account.