Hardware disease in cattle?

At first I laughed when I saw this ebay auction for an Alnico Magnet to help prevent hardware disease in cattle. My first thought was that New Age remedies have made it to livestock.... And "hardware disease"? really?

So I think about it for a while and do a web search and it turns out this seems for real. Cattle apparently will eat metal pieces they encounter and potentially infect/inflame their digestive tract. The magnets are fed to cows to stay in the stomach and keep the eaten metal from moving on into the more sensitive parts of the digestive tract where it can cause problems - or at least that's what's claimed. Seems plausible I guess. I'd never heard of it though. There's a wikipedia entry.