I think one or more might have been knocked over by the ascent stage when they left, and could be covered in a fine coating of regolith that actually may have protected them. The rest I'm sure are still there and looking a bit aged unless some alien souvenir hunters combed thru the sites.



The Jedi Master

'flag skeleton' Reminded me of this classic: http://www.theonion.com/articles/archaeological-dig-uncovers-ancient-race-of-skelet,1268/

As Jedi says, I think some ascent footage actually shows early landings blowing their own flags over. I'm not sure if later landings planted it further away as I think 'get the flag in' was pretty high up in the mission orders of the first landing.