According to this Cubed3 report, Vitei's Giles Goddard's confirmed that his team's working on a Balance Board WiiWare game for release later this year.
"Our current game uses the Balance Board actually, and it’s due out in September on WiiWare," he said. "So yes, much like Theta we came up with several prototypes of games and picked one that we thought was the most uniquely suited to the interface. The interesting thing is that the games you would think would work well with the Balance Board actually don't. So it should be interesting to see what kind of stuff gets made for it."
No further details were given on the title. A full interview with Goddard's promised "very soon".