Not sure, but I suspect an iPod/phone car charger that has a USB port, and thus will take the combined bluetooth/iPhone connecter cable, will work.
Here's one from Griffin (showing as out of stock here at everythingicafe):
http://store.everythingicafe.com/gri.../5A47A3871.htm
Here's a similar unit made by MacAlly:
http://macally.com/EN/Product/Articl...?ArticleID=185
And one made by ZipLinq:
http://www.amazon.com/Unlimited-Zipl.../dp/B000167V50