At this year's E3, Nintendo showed off Wii U "games" that were actually taken from 360 and PS3 versions.
According to one report, the reason for this was that developers only had access to "underclocked" Wii U development kits, able to produce games that weren't quite up to current gen snuff.
Sega West production boss Gary Dunn tells website Eurogamer that "there's another generation of prototype hardware coming out in June or July." These kits will provide game studios with key details regarding final Wii U hardware.
Dunn says this about the Wii U: "a lot of things are falling into place, in terms of how easy the machine is to develop for."