Nintendo has released another iteration of Wii U software. The latest update features a number of stability features and fixes that improve the performance of the Wii U user interface. It seems that the major improvement in system update 3.1.0 allows the Wii U to check for SpotPass data, Software, or System Updates when the Wii U is powered down.
These Wii U software updates will be installed while the Wii U is powered down, and system updates will be installed the next time the Wii U is powered on.
Nintendo also promises that a further update is scheduled for the Wii U this fall, which will add further performance enhancements for the system.