Sony Ericsson have released the SDK for their upcoming Windows Mobile-powered X1 handset. The SDK, as the name implies - Software Development Kit, allows users to specially develop software forthe X1, which, Sony Ericsson claim is to be released by the end of the year at the latest. The SDK allows users to develop a varety of panels for the X1. The panels allow quick access to a variety of things - games, images, e-mail, and so forth.