Don't forget Deinococcus radiodurans
AKA, D. rad:
http://antwrp.gsfc.nasa.gov/apod/ap060122.html
These little guys can survive 3,000 times the amount of radiation that
would kill us instantly. They "simply" repair their DNA.
Add to this a recent story on how solar radiation pressure pushes out
megatons of dust and other particles from their systems into the galaxy
at large - and if any microbes are those particles or riding on them -
then you've got a lot of panspermia going on among the stars.