The lower parts of Earth's atmosphere plays a roll in braking rather massive meteoroids I don't know the numbers, but this rock might have essentially dropped a part of the way down. It also could be a fragment of a piece of a larger meteoroid which impacted further away.
LC

http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20060710a.html

And at that, perhaps life even existed already during the tail of the earlier heavy one at the end of planet formation. Depending on crust formation times, obviously. That abiogenesis was sufficiently fast, on the order of ~ 10 ky, can't be excluded either.

With one "sure" opportunity (perhaps two) for launching Earth material, it must have happened, no? I should probably dig for impact models and simulations to see what amount of ejecta I can hope for.

And thanks Joe Hanford for the link, seems Meridiani Planum is an "erosion conveyor belt" for meteorites analogous to the Antarctic ones. (Though only concentrating vertically.) I still hold out hopes for seeing early Earth samples, before 3.5 Ga.

[For observing early life and its conditions. I dunno how large impacts would be required to launch samples though. Perhaps it's a pipe dream or at least very unlikely.]

Hell, any independent samples would probably be terrific, I'm not a geologist. But perhaps geologically active Mars is the easier meteorite find location than the dead Moon.

what is the scientific interest of going out of their way to study meteors on mars

At a guess meteorites are sufficiently rare to be worthy of study all by themselves. But I guess you would also get some idea of how these materials sort out through the solar system, their frequency, and how different environments affect them.

one feels compelled to ask, where is the "impact crater"?…

Quoting Hanford's link on Heat Shield rock:

Meridiani Planum, the part of Mars where this meteorite was found, is suspected to have once been covered by a layer of material with a thickness of as much as 1 km which has been subsequently eroded. This means that on impact this meteorite might have created a crater, but evidence of that crater may have been subsequently erased by millions, or even billions, of years of erosion. In any case, the meteorite does not show much sign of rust. In the absence of detailed knowledge of the Mars environment, it is difficult to conclude whether it fell recently or was buried until recently. It also shows little sign of weathering.

RT
http://www.anon-web-tools.us.tc

This will be the second meteor found by the rovers.. if confirmed.

I'm interested to know, where was the first one, and are there images of same?

Unless of coarse when the metorites struck Mars had a thicker atmosphere. It depends maybe when it struck but it poses some interesting questions.

There are several factors to consider Sili… Yes the atmosphere on Mars is much thinner but the meteor's approach angle and speed would also play a role in shaping the meteorite. It is also possible that there was more then one encounter with Mars atmosphere.

If the Martian atmosphere is thinner, the rocks won't get braked and baked as much when hurtling through it, right?