As discussed in this topic (http://forums.musicbrainz.org/viewtopic.php?id=2985) i would like to request adding one or both of those xmls to allow crossdomain calls with silverlight and flash. For an in depths explanation of these two files go here: http://www.devtoolshed.com/explanation-cross-domain-and-client-access-policy-files-silverlight
I would suggest to allow crossdomain calls from all flash and silverlight applications since theres no risk for abuse.

Thanks KeySam