How's this for a roller-coaster ride? Microsoft this morning told T-Mobile customers that it had been able to recover "most, if not all" of the personal data previously lost in a server failure at its Danger subsidiary, which supplies the software and services for the Sidekick devices.

"We plan to begin restoring users’ personal data as soon as possible, starting with personal contacts, after we have validated the data and our restoration plan," said Roz Ho, the Microsoft corporate vice president for premium mobile experiences, in an open letter to Sidekick users. "We will then continue to work around the clock to restore data to all affected users, including calendar, notes, tasks, photographs and high scores, as quickly as possible."

Should be interesting to see how Sidekick users react. On the one hand, it looks like they're getting their data back. On the other, the recovery follows a painful experience over the past two weeks. There's been no tweet on the subject yet from Perez Hilton, the celebrity blogger and high-profile Sidekick user who lashed out over the outage.

Some T-Mobile users had already filed suit over the outage.

Microsoft acquired Danger last year, and Ho is leading a Microsoft project to bring the Danger technology to market in new forms. In the letter, she apologized for the situation but said Microsoft now believes the data loss "affected a minority of Sidekick users." In addition, she said the company has "made changes to improve the overall stability of the Sidekick service and initiated a more resilient backup process to ensure that the integrity of our database backups is maintained."