Bruce Moomaw posted some abstracts from the Fourth Astrobiology
Conference held in Washington, D.C. last March on the UMSF forum:

http://www.unmannedspaceflight.com/index.php?s=&showtopic=2682&view=findpost&p=52362

One abstract caught my attention, which I quote here:

http://abscicon2006.arc.nasa.gov/agenda-session.php?sid=24 (#441):

Simulations of the effects of a Jupier-size planet migrating all the inward through the inner part of a forming solar system to within only 0.25 AU suggest that such an event -- contrary to accepted belief -- does not prevent the formation of habitable Earth-size planets in that star's inner system: "Although the migrating Jupiter-mass planet ejects a large amount of material, a significant fraction (10-40%) of planetary embryos remain after giant planet migration. Subsequent evolution of the system results in the formation of sizable terrestrial planets, often including a planet in the Habitable Zone (HZ). Planets formed in all simulations have high water contents from vigorous radial mixing stimulated by the migrating Jupiter. The non-migrating planet clears out the outer system, and accelerates the late stages of planet formation, but planets formed in the HZ are similar in both cases." If so, this will radically revise our search strategy for the Terrestrial Planet Finder -- which, at the moment, is scheduled not even to bother looking at stars that have been previously identified as having giant planets in their inner systems.

The simulation also found that such an inward-migrating Jupiter tends to cause the formation of "3-6 Earth-mass planets interior to the migrating Jupiter, ending up inside 0.1 AU, [which] are analogous to close-in, low-mass planets recently discovered around other stars."

So there may be even more Earth-like planets in the galaxy and beyond
than thought. And another point for life existing beyond our planet.