The notion of panspermia doesn't add to the creation/evolution debate in terms of origin of life, but only tries to explain the origins of life ON EARTH and requires that life arose elswhere in the universe, survived an interplanetary journey, found Earth, and our planet was hospitable. Despite this series of potentially improbable events, panspermia does have some high profile proponents, including Craig Ventner and Francis Crick.
Francis Crick, in fact, supports the directed panspermia view, though he thinks rather than specifically selecting Earth to seed, a more likely (and cost effective) scenario is that "seeds" were launched in all directions in hopes of eventually finding a compatible planet. Colonization of the universe is an interesting exercise in narcissitic altruism (at least in the sense of planetary catastrophes and ensuring the future of the human race). Given our current lifespans and foreseeable technologies, nobody who were to begin such a project would ever see any fruits from their labours and would simply have to be satisfied that thier DNA was out there somewhere and the species might live on. For an interesting essay on why space colonization can't happen, check out this blog.