The Windows Vista team just announced that the next version of Windows will not process any web feeds that are not well-formed XML. I think it is a good move and saves a lot of development headaches. Feed publishers should periodically check their feeds using tools such as Feed Validator to discover any potential problems and evaluate some of problems revealed by warning messages. Errors in your feed might result in your message not being delivered to your readers.
Tags: atom, RSS, windowsvista