One of the first demos Nintendo showed for the Nintendo DS was a voice chat tech demo that used the DS’s microphone, it looks like the project finally got revived and may be heading to DSiWare.
Nintendo’s website updated with a error code when using a code for redeeming Nintendo Points. Part of the errors description reads “To redeem a Nintendo DSi Download Ticket number, such as for the Nintendo DSi Speak Channel, enter the number off the Nintendo DSi Download Ticket in “Settings and Features” off of the main Nintendo DSi Shop page, then select “Nintendo DSi Download Ticket.”
This could be a mistake but I’m going to say that it is very likely that this is real. At the very least it might be more helpful then the Wii Speak Channel, and with DSi having a built in microphone it definitely opens it up to a lot larger user then Wii Speak has.