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.
Earlier this week, Aul disclosed that versions older than Windows 7 will require a full format and a fresh Windows 10 install although there are some relatively workarounds. Microsoft will be launching the next build, which could well be the Consumer Preview, at an event on its campus in two weeks' time. Windows 10, which some say could be free for Windows 8.1 users, is expected to be the most important product announcement of Microsoft in 2015.