Also received the same email; I am using the Facebook Connect plugin though (not Simple Facebook Connect). Worst part is that I just activated the plugin and integrated into my website this Saturday, and now I am already having to disable it?!? Not fair IMHO that we are getting dinged for use of third-party plugins that have been proven for quite some time now.
Unfortunately, we can’t count on the plugin developers to fix this in 48 hours as was already stated, so we’re up a creek without a paddle for now…hopefully someone will figure something out sooner than later.