Augustine: VOIP on WiFi ... new cell phones on an unlimited data plan can serve as WiFi hotspot; now the iPod Touch or iPhone can make VOIP calls for free over the data channel. Another hack enables video recording .. which means video calls with Skype over WiFi and over unlimited data plan is nearing! Long live telecom co's NOT! :-)
from Engadget by
Thomas Ricker 
Remember that
VoIP hack for the iPod touch. Right, the one that requires an
external mic. Well, mark your calendars Jailbreakers, the software will be available for download on New Year's Day. SIP-VoIP is free, but your donations will gladly (and rightfully) be accepted.
[Thanks, RadicalxEdward]