The system information screen looks the same as it did before Update 1 was applied.
That was the big discussion after it came out. No where did the OS actually list "Windows 8.1 Pro x64 with Update 1" or anything close to that. There is a thread about that on here, but I did not search for it yet this morning.
The ways you can tell were outlined by BlitzenZeus
. The other thing that helps show that you have 8.1 Update 1 are new icons on the start screen
The one on the left is "Power Options" and gives you the options of "Sleep", "Shutdown" or "Restart". The one on the right is "Search". Those icons are not present in Windows 8.0, or Windows 8.1 without Update 1 applied.
--Brian