System Menu 4.1 (Japan) released

Nintendo released a Wii Firmware update, version 4.1 in Japan. A bug fix to Wii Sports Resort, in which after playing a WiiWare/VC game off the SD card, and then playing Wii Sports Resort afterward, you would be forced to watch the how-to Wii Motion Plus video that normally plays only once on the initial play of Wii Sports Resort.

Before you turn on your Wii and download the new version, we are always warned that:

updating is not recommended until more information is known about its effects on homebrew

And here is the initial report from wiibrew (which was taken from 4.0) on affected homebrews

Source: ps3news