Still not working for me:

Firefox: 8.0
Flash: 11.1.102.55
Server: NA37

Method, go to gift notification from Globe emblem on FB page top left. Accept Gift. If it works, server selection pops up. Then I go back to FB home page and repeat.
This seems to accept more gifts than going directly back to the gift page. I seem to lose about 25% of gifts, with the "This is Not Your Gift" pop up.