@Phil (the Rignalda one, not the Pearson one ;-) ): actually doubly escaping is just the only right way to do it. If you want to put brackets or ampersand in, you need to escape them. If you put HTML in, you need to escape that. Those two rules are stacked: if you want to use brackets or ampersand in HTML, you need to escape them anyway and then just escape the full HTML stuff - you get doubly escaped chars for your literal ampersands or brackets. I don't understand the big rumble they made about this simple fact. Any programmer with half a braincell should know this already. But maybe it's like frederik guesses and there aren't that much programmers with half a braincell in the discussion ;-)
Sure, RSS is underspeced. But it's not as if there are no ways to find out if what you are doing makes any sense. So if you can't figure it out on your own, just check what people will see in some aggregators. The Reuters problem would have hit anybody right in the face if anybody at Reuters would have cared to test their feed. And sorry, but no spec - however complete it's definition might be - will safe you from stupidity like this.