Our twins have each gone through a biting phase. Initially, it was only one. The consistent response was to say "no biting" to the biter and remove them from the fun (not a formal time out until they were 1.5-2years old). The bitten got lots of hugs and ice and all sorts of attention. This started before they were 1.5, I think.
Often, we can see an attempt to bite coming -- it's usually when they're fighting over something. If we can break them up, no biting...
At this point (2.5), each has bitten the other. (One still uses biting more, but it's not exclusive any more.) Any biting now is a time out. (We go by the 1 minute for each year of age, so it's not a long time out, but it gets the idea across.)
I don't know about "picking up" biting. Our oldest was bitten in daycare, and never bit anyone himself. The one twin picked it up on his own -- he was often losing fights for toys, and it was his way of getting what he wanted... but the twins are home with a nanny during the day, so there's no one else for them to have "gotten" it from.
mommy to three boys: A, 3/04
and identical twins B and D, arrived 9/08