The app says "Learn Mandarin Chinese for Kids -- Numbers and Colors." It is by Kaeru-Life Inc., is available on the App Store and works on both the iPad and the iPhone (originally designed for iPhone/iTouch). This app is very well done. I paid 0.99 for it, and after today's class, realized that it was well worth it! (I hooked up my iPad to the LCD projector so the app was projected onto the whiteboard so the whole class could see it).
The great thing is that it teaches content and language at the same time. I was reminded today that some the 3 year old children have not yet mastered recognizing numbers (our standard numerals). Thus we began with standard numerals, and then when you touch that number, the next screen shows the number in Chinese (and a voice says the number in Chinese as well), and then they can choose a picture and count up to that number of the item pictured. This app gave students the chance to see the numeral, the number in Chinese, and then to count that number of an item. They can hear the numbers being spoken as part of the audio, and even learn a selection of vocabulary (transportation, animals, food).
There is also a second part of the app for colors. I haven't tried that with my preschool students, but, as we are also learning colors, I will most likely pull out this iPad app for teaching colors as well!