Arstechnica put up a tidbit of information and a picture of what appears to be a DS headset. Designed clearly to match the lite, this little beauty could make the Lite even better for just talking with friends (and hey, if you can share a game at the same time all the better).

Granted, I don't expect VOIP to be shivering in their boots, but having a headset instead of the on board microphone can come in quite handy. It looks like japan will be getting the headset in the September timeframe, no word yet on a US release. 
From what else I've seen online, there are a few places posting additional information.  http://www.hmv.co.jp/product/detail.asp?sku=1255027
I'm assuming (despite not having the proper encoding to view the page correctly), that the price is 1200 yen from what I can read.  Which would make this a fairly cheap product indeed, most likely a $14.99 or $19.99 price should it hit the US.

Origional article on Ars

In-Game voice chat will be supported in several upcoming titles for the DS.