It seems that VOIP app Skype will finally be released for the iPhone tomorrow (Tuesday). Gigaom.com had the original story:

SkypeIn and SkypeOut, along with Skype Chat, are the key features of this new version of the Skype application. This is a native P2P application for the iPhone and the iPod touch. It allows group chats and conference calls and is tightly integrated with Apple’s Address Book.

VOIP will only be available on Wi-Fi, but text chat should be available over cellular networks.
Update: It’s been released.