Some days ago Apple released iTunes 9.1.
This version dealt with a security issue related to MP4 files, although Apple will not disclose what they did.
This patch caused, in some cases, reeplay.it’s playlist’s RSS to stop working when syncing to iTunes 9.1.
We have been notified of the issue by some users, were able to replicate the problem, diagnose it and tried to find a workaround, which we did, tested and deployed yesterday morning.
We have been reported the issue is no longer present.