My dad works for NASA, and according to whatever I didn't filter out during dinner this weekend, it's a huge deal, since we've landed 3 times on Mars but failed 7, and this is the first craft (Spirit) equipped with super-cool robots looking for water, hydrocarbons, and other evidence of life. Another one is going to the other side of Mars on the 24th. (Opportunity)
That, and the pictures are the best quality NASA has ever had. They are all proud like only true geeks can be.