Whitney Tilson of T2 Partners says that Berkshire Hathaway is a buy, and says he thinks the housing market is headed for trouble. Tilson, one of the few to call the housing bust ahead of time, says he doesn’t think the housing market will see a “calamity”, but he does think millions more foreclosures are coming down the pipeline in the next couple years. He’s shorting housing-related stocks, with homebuilders being at the top of his shorts list.