As of May 31, the Danger service for T-Mobile Sidekicks will be no more.

It's the end of an era. T-Mobile announced this evening that it will discontinue its Danger data service to all Sidekick models starting May 31, 2011.

At that time, you will no longer be able to access data stored on Danger's cloud-based service, including contacts and photos. Internet and e-mail service will also be cut off. If you wish, you can still use the Sidekick for calls and text messaging.

T-Mobile will begin sending out letters to current Sidekick owners tomorrow to alert them to the change and provide information about transferring data and transitioning to a new device.

If you're one of the affected users, the first thing you'll want to do is get all of your personal data from the Danger service. T-Mobile provides a couple of ways to do this.

The first is through MyT-Mobile.com' there you will find a Web tool that can export your information, including contacts, appointments, photos, and bookmarks, to a new device, computer, or e-mail account.

The second method is to use the data transfer application, which is available from the Sidekick app catalog, and export all your data onto the Sidekick's memory card. You can then bring that card to a T-Mobile store and have a representative transfer the information onto your new phone.

The carrier said it will provide special offers on devices to Sidekick owners but didn't provide any specifics at this time. More information is expected in the coming weeks. It is T-Mobile's goal, however, to have the new Android-based T-Mobile Sidekick 4G available by spring, ahead of the May 31 cut-off date. Old phones can be returned to T-Mobile for recycling.

T-Mobile told CNET in a phone interview that the decision to shut off service was made jointly by Microsoft and Danger as a reflection that older devices must be replaced with newer ones. The carrier added that it was a natural evolution as the market transitions to new operating systems.

The first T-Mobile Sidekick (aka Danger Hiptop) debuted in 2002 with a 240x160-pixel-resolution, 4-bit monochrome screen. The most recent model was the T-Mobile Sidekick LX 2009.