Today T-Mobile posted yet another update about the on-going Sidekick data disaster story, but now the news is looking pretty good. According to T-Mobile "most, if not all" Sidekick user data has been recovered.Well, this is a relief, though poor T-Mobile and Microsoft (and their customers) have suffered a lot over the course of the past week. At first, Sidekick users lost their ability to connect to data services. Then users started reporting lost data. Over the weekend, Microsoft and T-Mobile said that all user data was lost and things got gnarly from there.

T-Mobile initially offered Sidekick users a free month of Sidekick data service, valued at about $30. When it appeared as though all user information was lost, T-Mobile kicked it up a notch and said it would also give those who lost data a $100 gift card. Yesterday, it indicated that it might actually be able to recover some data. Today, it says almost all of the data actually has been recovered. That's good news indeed for Sidekick customers (and for T-Mobile and Microsoft).

Microsoft said that a system failure destroyed its core database and the back-up systems. It has been working around the clock to restore those databases one step at a time, and says that as it proceeded, was able to recover more and more data. Users should see their contacts data restored first, followed by things such as calendar, notes, tasks, and photographs.

Both T-Mobile and Microsoft said they will take steps to make sure something like this can be avoided in the future. Here's the full letter from Microsoft and T-Mobile:

Dear T-Mobile Sidekick customers,

On behalf of Microsoft, I want to apologize for the recent problems with the Sidekick service and give you an update on the steps we have taken to resolve these problems.

We are pleased to report that we have recovered most, if not all, customer data for those Sidekick customers whose data was affected by the recent outage. 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. 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.

We now believe that data loss affected a minority of Sidekick users. If your Sidekick account was among those affected, please continue to log into these forums for the latest updates about when data restoration will begin, and any steps you may need to take. We will work with T-Mobile to post the next update on data restoration timing no later than Saturday.

We have determined that the outage was caused by a system failure that created data loss in the core database and the back-up. We rebuilt the system component by component, recovering data along the way. This careful process has taken a significant amount of time, but was necessary to preserve the integrity of the data.

We will continue working closely with T-Mobile to restore user data as quickly as possible. We are eager to deliver the level of reliable service that our incredibly loyal customers have become accustomed to, and we are taking immediate steps to help ensure this does not happen again. Specifically, we have 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.

Once again, we apologize for this situation and the inconvenience that it has created. Please know that we are working all-out to resolve this situation and restore the reliability of the service.

Sincerely, Roz Ho Corporate Vice President Premium Mobile Experiences, Microsoft Corporation