Up until now the Playstation Suite SDK has been in a closed beta but as of today it is now being opened up to more developers and the status is being changed to an open beta. The Playstation Suite SDK is a set of tools developers can use to create games for Playstation Certified devices whether it be the PS Vita or the Sony Tablet S and everything in between.
Developers are now able to download the SDK without having to try and register for the closed beta. The Playstation Suite SDK is available for free of course. Right now the Playstation Suite offers tools for performance verification but later this year it will officially launch the Playstation Suite SDK along side the Developer Programs for the Playstation Suite which will be a more complete set of tools for game development for Playstation certified devices.
No exact release date has been given as to when the official launching of everything will happen, just that it will be later this year. The official program will also allow licensed developers to distribute content through the PlayStation Store. All the information you need including signing up and SDK download is available here.
Website Referenced: Xperia Blog