Marco Arment, the creator of Instapaper, has written a blog post about an emerging problem caused by a change in the way iOS 5 does housekeeping: it now periodically clears out the "Caches" and "tmp" directories that some "offline reading" and map apps use for storing content, meaning apps will need to re-downloaded the content that has been removed -- potentially costing users in 3G data, or inconvenience when they are offline.
