A company called SHAPE Services has debuted a Web-based version Skype designed specifically for the iPhone. The service is available free "for a limited time." While the developers say the application doesn't require WiFi, other VOIP solutions we've tried on the iPhone have exhibited dismal performance when attempting to operate over AT&T's EDGE network. It uses SkypeOut credits for voice.
The Web app, dubbed "IM for Skype" is already available for BlackBerry RIM, Windows Mobile Pocket PC, Palm OS, Symbian and J2ME devices.