If you're diligent in your record keeping where WoW
is concerned, you probably have a bunch of saved chat or combat logs in your Logs folder. Well, back those suckers up, because when 5.0.4 hits, all of the data in that folder is being deleted. Nethaera provided this helpful notification on the official forums:
Save Your Chat Logs
With the upcoming release of patch 5.0.4, all items within the Logs Directory for World of Warcraft will be deleted. It is advised that if you have WoW Combat Logs or WoW Chat Logs that you would like to save, that you do so prior to the release of the patch.
It's not like saving them is a big deal, of course -- you can just move them to a new folder and you're fine. Good on Blizzard for letting us know, at least; now everyone can save their combat logs from Molten Core and their extended ERP sessions in Goldshire or whatever.