I Tivoed it and was gonna watch it tonight. The program description said "4 billion years ago a planet the size of Mars hit Earth and turned it from a barren wasteland into the planet we know now". I wasn't aware it was gonna cover the Earths axis wobbles, which is due to happen again on Dec. 21, 2012.
I was actually going to start a thread about this, or cover it in one of the prvious world history/future threads. I'm sure after I watch it i will be able to tie it into something already discussed here
On another note I did watch a program about some caucasian mummies found in the middle of a desert in China that date back to the times before Marco Polo even ventured from the west into China....very interesting.