The latest issue of Famitsu includes an ad that suggests the folks at Nintendo of Japan may be about to unveil a new Tingle game. Here's a scan of the ad, from http://wiieveryday.blogspot.com:
Considering the DS logo in the upper-left-hand corner, it seems to be a safe bet that the game will appear on Nintendo's world-dominating handheld (as opposed to its world-dominating console, the Wii), but that's about all that can be gleaned from the ad.
Hopefully more will be revealed soon - and hopefully this title will be released in North America, unlike the Japan-and-Europe-only Freshly-Picked Tingle's Rosy Rupeeland. I'll be getting it regardless, I'm sure...
Upsate #1: The Japanese text above Tingle says, "Fairy?"
Update #2: Nintendo of Japan has launched a website for this as-yet-unnamed game. Apparently, a trailer will be added to the site on June 18.