If you host your SWF on S3 and your HTML wrapper on someotherdomain.com, BookmarkManager won't work, even if you call Security.allowDomain("*").
Please see my comments on this bug for more details: https://bugs.adobe.com/jira/browse/SDK-24639
Any suggestions for a workaround would be greatly appreciated. [crossing my fingers that Alex Harui is checking the forums today ]
I'm using Flex SDK 4.0, BTW.
I added a comment to the bug. It might just be a configuration issue.