IMHO, they already have some very convincing evidence of life. But I imagine there's alot of people being consulted about the whens, wheretos, and hows about making the announcement.
I agree. I showed my son and husbanad a photo today that was posted on another thread. I am was a geologist, my husband was a mining engineer, and my son took earth science courses. All three of us agreed it looked like a crinoid fossil.
The implications of fossils on Mars need to be thought through and such an announcement is not to be made lightly.