It's really an awesome discovery. It's right up there with the discovery that we orbit the sun, in my opinion.
It completely redefines the scope of probability of life on other planets, and hopefully it will fuel expanded research into this field.
Think about it... with this, we are once again in the position of legitimately considering the possibility that life or even intelligent life other than ourselves exists within the bounds of our solar system. We also have a legitimate basis for the theory that life on this planet originated elsewhere.
I guess I'm a science-nerd from afar (okay, I do write Scifi'), but I'll have trouble sleeping tonight, because I'm so excited. NASA is having a press conference about this tomorrow.