Tell us where you stopped and we can tell you what's new.
Because, there are chances that you already know a lot as lot of homebrew where already released 4 years ago. (even more seeing you already posted in threads for wii hacking guide, even if not the best one you picked up)
Also, tell us if you want a global update or specific updates (nintendo updates, release update, hacking update, piracy update ?)
What's new (you may or may not know) :
- Gamecube backups can be played on both Wii and WiiU, from SD and USB from a FAT32 partition. (that's probably the best improvement since you left).
- Nintendo ended its network support (online game).
- A custom network has been developed to replace nintendo's, by patching games to replace the network URL.
- and ... well... maybe that's all ?
If you want specific information, ask for them specifically.