Why, you ask? Fundamentals, fundamentals, fundamentals.
It is simple. Investors "see that many of the companies trade at a discount to their net asset value, a key measure of the underlying worth of the company's real estate value, and therefore represent good deals. They were also encouraged by the REITs' continued access to capital throughout the recent credit crunch." And as the story also says, a lot of people think this is a good time to be a landlord.
It also looks like 3Q earnings will be important. Many of these guys stayed out of the private buying frenzy, so as prices correct, REITs and their money (or access to money) may jump into the acquisition game.