Basically it's where you put all of your PPC earnings into your own PPC advertising campaigns, which generates yet more traffic and PPC earnings to spend on PPC advertising. A kind of continual circle. That's my understanding anyway.
hello, buying cheaper traffic and reselling it with profit... more here: http://blog.searchanyway.com/2008/01/search_arbitrage_a_global_over.html hope that helps.
it's buying PPC traffic from cheap PPC Ad Company and Direct this traffic to high bid keyword on another PPC Company on the hope to pay 5c per click on the first ppc and you get 0.5$ per click on the second ppc
The last two posts are correct. The term used to be used mainly in the context of buying cheap ppc traffic and sending it your own high paying ppc ads. For example, someone would bid on long tail terms or mispellings and send the traffic to page full of YSM or adsense ads that pay much higher. Obviously Google has cracked down on this now although it still happens. The term can still be correctly applied to PPC -> affiliate offers as well though.