Team XLink has announced that they have successfully tunneled PictoChat over the Internet (i.e., one DS through a PC over the Internet, to a 2nd PC, to a 2nd DS). They have not made the details of their implementation public yet as they are working on perfecting and stabilizing their requirements and procedures, but assure that there will be a more demonstrative announcement when they reach that point (hopefully soon).
You can read more about it (along with all of the skeptics) over at this thread on their forum. This is obviously a very nice accomplishment and a small but important step for the fledgling DS homebrew scene. Congratuations to them. Now everyone back to work :)