Skype has launched a preview of Skype for BlackBerry, however the app requires you have BlackBerry 10.1, which won't reach the market until the launch of the Q10 smartphone. So sorry Z10 owners you'll have to wait then to have a play with it.
Full description of the app
Free voice and video calls to anyone else who is on Skype, whether they’re on BlackBerry®, Android, iPhone, Windows Phone, Mac or PC. Send IMs to your friends and family, no matter where they are. Features: - Skype to Skype IMs, video and voice calls are free* over 3G or WiFi. - Make low-cost calls and send SMS messages to mobiles or landlines from your BlackBerry® smartphone.
- Send pictures, videos and files to any of your contacts.
- Enjoy high-quality sound when you call anyone else who is on Skype.
- Talk face to face or show what you’re seeing with front and rear-facing cameras.
- Talk to your Windows Live Messenger friends on Skype. Sign in to Skype with your Microsoft account and have your Messenger, Hotmail and Outlook contacts in one place. For more information, visit the Skype for BlackBerry® FAQ page: http://www.skype.com/go/help.faq.blackberry * Operator data charges may apply. We recommend using an unlimited data plan or WiFi connection
Source: BlackBerry World