It's mundanely obvious that interstellar travel is perfectly feasible for an unmanned probe that can expect to be discovered intact after a billion years or so by an alien race that didn't exist when it was launched. Travel or transport LIVING BEINGS just isn't going to happen, though, without a space fold or something similar. Or -- as Gary mentioned -- if a civilization evolved near the galactic core or in a dense cluster of stars, in which case interstellar travel only takes slightly longer than interplanetary travel.
What about creating an artificial wormhole like they depicted in the film Lost in Space
One of the more likely scenerios for non-linear space travel, but still, the energy to form a wormhole is problematic. I am betting against this simply because of the Fermi Paradox...I think there ARE aliens out there slogging through space one sector at a time using sublight means and equipment that is small and difficult to track with our technological level.