Hi there... you can still visit the cockpit after 9-11, I would do it all the time on my United flights and on a Southwest flight. I was even let to sit jumpseat on the ground in DEN (to SFO) for the preflight on a UA 767-322/ER... than the Captain suggested the FO to get up and take my photo in the right seat
. Those pilots were very friendly and the FO said he was considering the same camera I was using, so I gave him a short review and told him where and how much I paid for it...Just one of the reasons UA is the best...And this was just a few months ago in February.
On my most recent NW flights last week, I was denied...and I only asked the FA at the door while deplaning to take a photo of the flight deck after the BIS-MSP flight (DC95). But I believe it was because the pilots weren't in there at the time... and I think the FA thought I wanted to sit there or something... lol... only a photo lady!
Good luck! All depends on the crew and what mood they are in....