http://marsrovers.jpl.nasa.gov/home/index.html
The two 90-sols-in-90-seconds movies are well worth a watch if you are interested. See your 800 Million USD at work in time-lapse mode.
They might be slow in real time, but the two rovers have traversed some pretty nasty terrain. Well done Spirit and Opportunity!
Sorry, no aliens to be seen. Oh - except the rovers of course, as they're Aliens on mars.