This is what I got from the Google Translate of the news source, (of which this is the link btw:
http://news.walkerplus.com/2010/0928/2/)
In the CM, they use classic love ballads, like the one's of Edith Piaf, and some other Japanese singer, but I'm not sure of Utada has covered one of them, written a new song that sounds like it, or they just use one of the old songs. Will update this or post a new posts once I've found out more. Omg I'm so excited!!
Edit: okay she seems to have covered Edith Piaf's Hymne à l'amour, the CM airs October 2nd and the Chaku-uta will be released September 28th.
Edit 2: she has a twitter account: @ utadahikaru. Also these: @ u3music and @ hikki_staff. Also, there's something about a Pepsi concert the 8th and 9th of December in Yokohama Arena and she seems to be performing but I'm not sure.