Skype's iOS app for iPhone is avavilable now with video calling. The software vendor has a barebones, almost terse, blogpost about the 3.0 release.
Download the 3.0 version from the App Store to an iOS 4.0 device and you can place video calls to other iOS 4 devices and to Skype-equipped PCs and Macs.
The calls, unlike the current version of Apple's FaceTime video chat program, can run over 3G connections as well as Wi-Fi.
You can start or receive free Skype video calls on iPhone 4, iPhone 3GS or iPod touch 4th generation with iOS 4.0 or later firmware. You can videocall with computers running either Skype for Windows 4.2 or later, or Skype for Mac 2.8 or later, or Skype for Linux; or with the ASUS videophone. You can only receive video calls if you have an iPad or iPod touch 3rd generation, because these devices lack a camera.
Adding bandwidth-consuming video could put more stress on Skype's own peer-to-peer network. The Skype system suffered extensive and prolonged outages in December 22-23. On December 28, Skype CEO Lars Rabbe dissected the causes of the disruption and pledged that the company was strenghtening its network to prevent a recurrence.