Well... conspiracy theorists will have a field day with this. I think it's just... creepy, for a lack of a better word at the moment. No matter where you go your iPhone has made a note of it.
In fact, this morning, my notification screen told me it would take "about 16 minutes to get to work." Keep in mind I've never told my iPhone where I work :) So, year... I'll stick with "creepy."
You can turn off the feature. See how...and the complete story from Yahoo! by clicking here.