SoMa: With eight hot dog carts or shops now scattered, a quickly-growing What's Up Dog empire is now expanding into the full-service restaurant arena. It's no Doggie Diner, but the gourmet sausage vendors are taking the diner approach on the corner of Howard and 12th. Prices are low and the menu has most diner staples (and the gourmet dogs too), but as a tipster points out, "one wonders if maybe Whats Up Dog might've been a better fit for the Mercury space over on Folsom where there's actually some nighttime foot traffic (and since I haven't seen a single person eat at the Mercury since it opened)." Nonetheless, the diner—which is hoped to debut in the next few days—could be a nice addition for the SoMa folks in search of decent cheap eats. But really now, let's talk about that 9pm closing time ..