At Mobile World Congress in Barcelona on Tuesday, Skype and Verizon Wireless announced together the launch of Skype Mobile, a free application that will run on select Verizon smartphones.

The application was co-developed by the Skype and Verizon teams and according to the two companies representatives it will be launched late in March on nine different devices, including:

• BlackBerry Curve

• BlackBerry 8830 World Edition

• BlackBerry Storm 1

• BlackBerry Storm 2

• Motorola Droid

• HTC Eris

• Motorola Devour

The application will be a free download. It will run in the background on all of those phones. Also Skype representative mentioned that the company has worked very closely with Verizon to maximize battery life and call quality. All of the Skype calls will go through the data plan and will not count as cellular minutes.

Skype and Verizon also hinted that there would be some address book integration that will show the Skype presence of your contacts. That allusion at deeper integration beyond just the development of a stand-alone app. The software itself was not demonstrated at the press conference.

A few additional statistics that came out in the event:

• Verizon has 90 million U.S. wireless customers

• Skype has 500 million users

• Skype is adding 300K new users per day

• Verizon stated that Skype calls will not negatively impact their 3G data network. John Stratton, Verizon chief marketing officer, announced, “We won’t let network quality erode. That’s the cornerstone of our brand.”

This is a great deal for Skype. They get the best U.S. 3G network and an early jump on access to Verizon’s forthcoming 4G network. However, they had to sell a bit of their soul to do it. This application will be exclusive to Verizon and it sounds like Skype won’t be making deals with any other carriers for a while. The big question is how exclusive is this exclusive deal? Can Skype continue to develop Android, iPhone, BlackBerry, and Windows Phone apps?