How many times has this come up here in BHW?? lol
I, as well as many others, have answered this question time and again...
Guys, please use the search function!
Ok, now that my rant is out of the way, duplicate content will not get you banned in any way, but you definitely don't want it on the same site.
If you are going to post duplicate content on different sites like different Web 2.0 sites, then there really is no problem. I do this all the time, get ranked, and make money.
With that said, this is more of a quick hit strategy, and your rankings may fall a bit in the SERPs as time goes on and Google updates.
But there is no big time penalty. It's pretty much a myth.