I got my corporate Amex in 2008. There was no pull on my credit whatsoever, and the do not report that card to my reports. When I got my own personal Amex in December 2011, they backdated it to the 2008 date on the corporate card (upon my request), and show "OK" history on all 3 credit reports going back to 2008.
Starting Score: 660 Jan 2012