That leak was discovered while perusing the "error code 206602" entry at Nintendo.com, an entry which has since been scrubbed of any mention of the Nintendo DSi Speak Channel. Searching Google for that entry shows its former existence, which previously read: "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.'"
If true, it wouldn't be the first resource for DS or DSi owners to utilize voice chat. Previous Nintendo DS games, such as Metroid Prime Hunters and Advance Wars: Days of Ruin, had voice chat over wi-fi built-in.
A DSi Speak Channel definitely sounds in line with the company's plans to offer such functionality via the DSi Shop, not to mention falling in line with Nintendo's naming conventions, looking at Animal Crossing: City Folk's Wii Speak accessory.
What do you think? Would you pay for a Speak Channel on the Nintendo DSi? And just how high are you willing to go?
Nintendo DSi Speak Channel in the works? [Kolma.info]
Nintendo error code support points to DSi Speak Channel in the works [GoNintendo]