What if we take microbes/bacteria to mars?

Factual Questions
1

I have searched the straight dope archives and found threads relating to the threats of bringing back Martian microbes:

http://boards.straightdope.com/sdmb/showthread.php?t=193752&highlight=mars+microbes+bacteria

I will probably even get the same answer here, but I want to know if scientists are taking precautions to limit the life we introduce to Mars. Could Earthly microbes/bacteria be a threat to possible Martian life? This might be a little too Sci-fi, but could this possibility start evolution on Mars? That is if we introduce microbes and they survive. … Maybe I have read too many books by Arthur C. Clarke.

2

Check out this article from 2001. Basically: yes, steps are taken to make sure that we don’t introduce E. coli to Mars, but they aren’t foolproof; and we also have to make sure that if our sensors detect organic compounds on Mars, that it isn’t some dead cellular residue from Earth giving us a false positive.