There is a linkage program at Columbia, but as Johnny_D says, it's rather competitive so students in general shouldn't count on being accepted. For reference, the linkage programs there are Brown, Jefferson, MCP/Drexel, SUNY Brooklyn, SUNY Stony Brook, Temple and Trinity (in Ireland). I think there's one in Israel too, but I'm not certain. If a student doesn't link into any of those programs, they have a "glide" year like everyone else. Other postbac programs may (and probably do) vary with their mode of operation, so if you're interested in a specific program you may be better off asking them directly.
On a side note the advisors at Columbia say the "glide" year isn't necessarily bad, and can be used to get more experience under your belt either by upper-level science courses or a research position--either of which may catch the interest of med schools you're applying for.