Skype fans can finally rejoice as 3G cellular data calling has been added to the latest Skype iPhone app, version 2.0. The feature has been long-awaited by Skype users. VoIP (Voice over Internet Protocol) calling doesn't use up cellular plan minutes, although it does use data bandwidth.

Previously, Skype users were limited to making calls with the iPhone app on a Wi-Fi network. Several other apps have already added 3G VoIP support. Skype 2.0 is currently free of charge, although the company may start charging a monthly fee for 3G calls starting in 2011.

Where will Apple bring its iPhone next? Most of the speculation revolves around Verizon Wireless, the largest cellular carrier in the US. There are new rumors that Sprint could also benefit from an end to the the exclusive iPhone agreement Apple and AT&T have had since 2007.

Any move to Verizon or Sprint would make a CDMA iPhone necessary, while service on T-Mobile and AT&T already work with the current GSM model iPhone. Several sources have told MacRumors that Sprint is preparing for an iPhone 4 release on its network in September 2010.

Some really useful and interesting features are on their way in iPhone OS 4.0. The operating system is expected to launch this summer with Apple's next generation iPhone hardware. The same firmware will make its way over to the iPad in the fall.

iPhone OS 4 beta 4 includes ample evidence of video conferencing, including a "Video Calls Debugging" section on field test models of the latest hardware. Speaking of the hardware, a lost iPhone 4 in Vietnam was broken down and found to feature Apple's A4 processor, the same powerhouse that runs the iPad.

It's only happened once before, but another iPhone model is about to become history. The iPhone 3G was launched on July 11, 2008, meaning early adopters of the model will see their two-year service contracts expire just as their devices become one step closer to obsolete.

Apple recently announced the original iPhone (iPhone 2G) would not be supported in iPhone OS 4, the latest and greatest iPhone operating system coming this summer. Although no such announcements have been made about the 3G model, supplies are said to be short and reports have indicated that Apple has ceased shipments of the device.

AT&T Wireless plans to increase their early termination fee (ETF) on all smartphones from $150 to $325 starting on the first day of June. For those who are happy with their service and plan to keep their iPhone there's no reason to worry. If you're interested in breaking your contract before two years is up, there's less than a week to act before you pay 86% more.

Verizon Wireless recently jacked up their own ETF charges to $350 for smartphones. The reason why many carriers charge this fee in the first place is to help recoup their investment on subsidized mobile phones. If customers bought a cheap phone and immediately quit their contract, the wireless carrier doesn't have time to make up the difference in monthly service profits.