The presence of ice has been known for sometime (even polar caps and glaciers). The significance here is the presence of liquid water and it’s implications in the search for life.
They haven't actually discovered flowing water, only "evidence" of possible flowing water. They see changes in the poles where it frosts/freezes and then thaws in the Summer. We've seen the frost, ice and gullies back in the 1970's, so this really isn't anything new.
As far as life goes, we've drilled/ground and analyzed countless rocks and bits of sand (Spirit and Opportunity) and examined them with spectrometers, xrays, microscopes and all sorts of tests, and have yet to find any signs of any past or present organic material at all.
You can't examine any sample of sand on Earth without seeing bits of broken shells or other signs of past life. On Mars, we've seen nothing... zilch.