The DNG specification is now updated to the version 126.96.36.199
It is available here.
Note that this document is targeted for software developpers, but might be an interesting read to understand what DNG really is. The fact that the DNG file format is properly documented contrasts with the proprietary file formats currently used by camera manufacturers.
Thomas Knoll explains here that the DNG converter 2.4 is still outputting DNG spec 188.8.131.52, with some 184.108.40.206 tags, but that software developpers should read the new specification in order to update their third-party software for future versions of the format.