Can I date stamp photos on iPhone 4S?

The image file is date-stamped, and any photo editor app on your computer can view the date and time, but I don't know of any way to display a visible date stamp. There may be 3rd party camera apps that can do this.

Just to expand on what Lawrence Finch posted. Tell Apple about about your need to date/time stamp photos

Go here > http://www.apple.com/feedback/