Skype has shut down Extras, its developer program, because the company said it was not being used by enough developers to warrant continuing it, according to a TechCrunch post. The program allowed developers to make Skype-based plugins that use the Skype network in other applications, but commentators like Michael Arrington and Om Malik said the program never allowed Skype calling ability to be integrated deeply enough with the other applications to drive significant volume of development activity.

Malik held out hope that Skype’s new owners might institute a more developer friendly program to create new ways to use Skype with third-party applications, which could expand the service’s utility and also drive revenue growth.

He said the move to shutter Extras would be detrimental to Skype’s long-term growth, as the developer community would turn to other services potentially causing innovation around Skype to flag.

Given the choice between developing for the iPhone or Skype, I would choose the iPhone right now. However, the landscape is always changing.