It seems that this 3rd iteration of Wii firmware also will prevent you from using Datel's Freeloader disc, which is used by people who want to played imported Gamecube games. This wasn't announced by Nintendo, and may simply be a side effect of other changes. Datel has commented that they do not know if it was intentional or not, and are working on creating a workaround. As the article mentions, whether or not Nintendo meant to do this could impact anyone using the Datel disc:
The question remains as to whether Nintendo purposely made the firmware update to have this consequence or if it is just an accidental compatibility issue. Nintendo refused to comment on the matter.
Normally, game developers frown upon people playing games that weren't intended for their region. Sometimes due to compatibility issues, sometimes due to legal issues, sometimes due to them just being all huffy. Regardless, there are many who enjoy getting games from other countries. It would be a shame if Nintendo moves to block them.