Same problem here.
I tried my old portable tekkit, downloaded the technic-launcher-latest.jar (http://mirror.technicpack.net/files/technic-launcher-latest.jar)
and after downloading Minecraft.jar it fails to update.
Would try the .exe, but the Download isn't working (http://mirror.technicpack.net/files/TechnicLauncher.exe)
EDIT
tried to delete the voltz-folder and start voltz,
and deleted my tekkit and technic-folder
EDIT2:
Website is up again, asked in IRC the website had some load balance problems