It's official: the Skype application for iPhone and iPod touch should be available tomorrow on the App Store at no cost. As expected, the upcoming client will include free Skype-to-Skype calls and SkypeOut support over Wi-Fi only as well as interface integration and instant messaging to other users. Users won't be able to place calls over cellular networks, which certainly comes as a disappointment, but with Wi-Fi networks becoming so widespread at least some users will save on international calls and roaming costs from time to time.

Users can already get Skype for the iPhone using third party apps, like Fring or Truphone, but the official app will supposedly have better voice quality and lower latency. Skype for iPhone is still rather short on features compared its desktop counterpart, though - it handles conference calling only as a participant, not an initiator, and lacks support for things such as voicemail, file transfers and SMS. PC World has a hands-on preview of the upcoming VoIP application which you can check out here. A version for several BlackBerry models will be available in May.