Confirm NSIS installers work in Windows8 WinRT tablets and/or Pro Desktop situations; possibly make them look more Metro (form maximized, no window form border, bigger kindergarten buttons for use with touch screens...)
Normal Windows (Desktop) apps are not going to work on WinRT (ARM) because MS wants to kill the desktop (IMHO) so they don't allow Win32 apps (except IE and Office) on that platform AFAIK.
We will add Win8 support to WinVer.nsh once it hits RTM and the final build number is known, other than that I don't think there are any plans to change anything for Win8. If you just treat Win8 like a broken version of Win7 you should probably be OK :)
If you have a problem with UI widget sizes you should change the text size/DPI on your system...