From the VAG-COM Yahoo forum:
Release 512.4 is now available on our download page.
* Several small bug fixes and compatibility enhancements.
* Support for redesigned (Rev. C) KEY-USB interfaces.
* Updated Label files, including Long Coding XPLs & AutoScan
- Thanks to Sebastian!
* Updated Long Coding Helper
- Thanks to Niels!
If you're using 512.1 please consider this a "Service Pack" and update.
Direct link to download page: