Okay.. Nintendo published a new update for the Wii shop channel.. however.. IOS files are also replaced... and that changes the system functionality:
Summing up gbatemp posts it seems:
-HBC still works after installation, Gecko OS also does
-Twilight Hack 0.1b still seems to work
-
HOWEVER, HBC installation fails
-All IOS files are signature fixed - this most likely means that even Gecko OS can't run trucha-signed discs anymore
-Backups and Imports with modchips are unaffected - they still work
-Wii Shop channel is not accessible if you continue using 3.3 or older
-downgrade using WAD manager or related tools to 3.2 or 3.3 does not seem to work
All information is just a mash-up of GBATemp posts.. no warranty!
UPDATE: If you just want to have the new Shop:
http://wiibrew.org/wiki/Wii_Shop_and_IOS51_installerThanks for everyone on these links!
UPDATE 2: The homebrew channel can be installed if you use the new version (beta9). The installation won't fail!