I was just going to post the same thing. My little girl is 13 months and I saw the cutest knitted jumper on a girlabout that age in Germany, I knew I had to knit one too.
The only pattern I have found is in the little princess dress in one of the Yarn Girls books. It is not exactly what I'm looking for but similar. You can check it out on their website www.yarnco.com
Let me know if you find something else.