Skype this morning took a moment on its blog to explain why it has lagged in the release of a 3G version of its popular VoIP app for the iPhone. In conjunction with the release of its iPad, Apple recently rolled out a new SDK for the iPhone that allows for VoIP calling over 3G. Previously all VoIP calls were restricted to Wi-Fi.

According a post this morning on Skype’s Web site, the company was holding back with its 3G version in hopes of improving audio quality before it releases the new version of the app.

A video posted on the blog, which features an informal interview with David Ponsford, the lead on Skype’s development team for iPhone, said the new version will include wideband audio, which allows for greater clarity and fidelity. He also noted that the forthcoming version of the Skype app for iPhone will include a call quality indicator, which changes from red, to yellow, to green, depending on the coverage.

Ponsford promised iPhone users won’t have to wait too long, saying the new app will be “coming real soon.”