If you are just amending a passport by changing a name due to marriage will your passport number change?

Answer

No, you receive your original passport back, with information printed on the back page regarding the amendment date and content.  

Answer

The above answer is correct that you do receive your passport back if you have more than a year validation remaining with a notation on the front page of the passport directing customs to look on the last page of your passport for the amended name.
However, please keep in mind that most Asian countries will not accept an amended passport. In my case i had to make a speacial request with the passport agency explaining that the People's Republic of China do not accept amended passports and needed a new passport which did change my number for legal entry in to China.


Comment:
I had my passport amended to state that I had a name change. It was on one the last few pages that are there just for amendments. I lived in China (Shanghai and Shenzhen) and traveled around Asia quite a bit (Singapore, Taiwan, Thailand, Malaysia, Hong Kong, Macau, Philippines, Indonesia, and a few other countries). Not one country had a problem with my amended passport. I always filled out forms with my new name and when they asked about the difference in name, I just directed them to the back of my passport. There was no notification on my front page in regards to my name change. I did this for about 2 years before I needed a new passport due to lack of blank pages for stamps (I go through one passport every 3-4 years). On a side note, my passport was amended by the American Consulate General in Shanghai so maybe that made a difference?




It may have changed
http://travel.state.gov/passport/get/fee/fee_2654.HTML