Following on several days, and to a lesser extent months, of really good news, the big boys are making noise that may be immediately appealing to many borrowers, but may not be so hot for the market as a whole. Freddie Mac has hinted that more low-down-payment products could be on the way. Of course, low down-payments help many people into homes. But on the other hand, they enable people to buy more home, drive up prices, and may lead to another bubble.