I received another email from Western Digital yesterday, here it is:
Dear WD Registered Customer,
As we previously announced, Western Digital received reports of Western Digital and other external HDD products experiencing data loss when updating to OS X Mavericks (10.9). Our investigation to date has found that for a small percentage of customers that have the WD Drive Manager, WD Raid Manager and/or WD SmartWare software applications installed on their Mac, there can be cases of a repartition and reformat of their Direct Attached Storage (DAS) devices without customer acknowledgement which can result in data loss. We have an updated version of the software that fixes this issue. We strongly recommend that you install this updated software. Please contact our service and support team with any questions.
Below are links to download the software:
Western Digital announced the issues customers were having earlier this month and have done a good job of keeping everyone informed. By installing these latest software versions the old versions (if still present) will be automatically uninstalled and it should be safe to use your WD external drives again. Keep in mind that for WD drives to work you don’t need any additional software for it to function. You just need it for additional functionality like configuring a RAID.