From time to time, new versions of the GFDL may be released. They often include some extra clarifications, tidy up some loose ends, but are still basically the same license.
Most Wikipedia content is licensed under GFDL version 1.2, or later version published by the Free Software Foundation, but Wikipedia formally only used version 1.1. Because GFDL licenses are perpetual and cannot be retracted, you can continue to use old Wikipedia content under the 1.1 version, should you wish to do so, though you can also choose to use it under the 1.2 or 1.3 versions (or any later version published by the FSF). However, text submitted after the switchover date cannot be used under version 1.1: only version 1.2 or later.
Remember that we cannot give legal advice in relation to your situation and your use of Wikipedia content.