In recent usage, the phrase signing statement has referred mostly to statements relating to constitutional matters that direct executive agencies to apply the law according to the president's interpretation of the Constitution.
You might need to exercise a little bit more patience. Though Microsoft (MSFT, Tech30) said a month ago that Windows 10 would become available on July 29, Microsoft clarified on Thursday that everyone won't be able to upgrade on that day. Microsoft will roll-out upgrades slowly, in waves.
The good news is Windows 10 comes with a lot of promises for enterprise and government customers, particularly when it comes to security (read our take from Nov 2015). One of the major advances is enhancing OS security.