Ed Koch and former Council Speaker Peter Vallone have been hanging out together at Columbia- Presbyterian, kind of like when they ran the city government — only with hospital food. Vallone, 77, was having a stent put in to fix a clogged artery, and sneaked out of his room to go pay his longtime friend a visit. “[Ed] looked better than he’s looked in a long time. He really looked terrific. Whatever is happening, he’s looking a lot better. I told him that,” Vallone, who’s now out of the hospital, told us. “Since our birthdays are 10 years apart . . . I said I expect he’ll live another 10 years so we can both one day be centurions.” Koch, 87, is being treated for anemia. His rep said he expected to be released today.