Sony Ericsson wants Windows Mobile developers to start working on applications for its Xperia X1 and on Wednesday it announced a tailor-made SDK (software development kit) for the upcoming smartphone.

A beta version of the Sony Ericsson SDK for Windows Mobile 6.1 is available for download from the company Web page. It has already been used in-house and by some partners to develop panels for the user interface, according to Merran Wrigley, spokeswoman at Sony Ericsson.

Sony Ericsson isn't trying to build a new developer community; instead it wants to take advantage of what's already there, according to Wrigley. The SDK is based on Visual Studio, with extensions for the Xperia panel interface. "It will feel very familiar to existing Windows Mobile developers," said Wrigley.

Using the SDK developers can adapt existing Windows Mobile applications, and start working on new ones. It currently supports HTML, CSS (Cascading Style Sheets), C and C++, according to Wrigley, who didn't want to announce when a finished version will become available.

The Xperia X1 was announced at Mobile World Congress in February. It is a slider phone, with a 3-inch display and touch navigation. For surfing the Web it supports Wi-Fi and HSPA (High-Speed Packet Access), for both downstream and upstream traffic. Just like most other high-end phones it also supports navigation using A-GPS (Assisted Global Positioning System).

Lately, there have been some reports stating that the phone has been delayed, but the official Sony Ericsson line is still that the phone will ship during the fourth quarter, according to Wrigley. As the fourth quarter starts it will announce more details about when and where the phone will ship, so far selected markets is all the company wants to divulge.