Sony Ericsson has published the software developer kit for its coming-soon Xperia X1 that's free for developers to download.

Inviting developers and content creators to create mobile content for the phone using the Windows Mobile based SDK, Sony Ericsson says content be created in categories such as music, photography, email or instant messaging, gaming, social networking or video applications.

The touchscreen interface centres around nine interactive "panels" and panel applications could include search engines, advanced calendar or social networking applications, music or film catalogues, sports or news related content.

The Sony Ericsson SDK for Windows Mobile 6.1 will be made available for download on the Sony Ericsson Developer World website: