SMSBackup is a free homebrew app that backs up SMS messages on interop-unlocked Windows Phone 7 devices. Although it can backup all the SMS, it cannot restore them to the Messaging Hub yet. But at the same time, you can import previously exported messages into this SMSBackup app, which then shows them in a readable format, sorted by conversation or time stamp. The app actually picks the “CommsBackup.xml” file, which contains all SMS messages older than a day, and then copies to the phone or skydrive.

Features of the app;

• Automatically import sms in “CommsBackup.xml” to the app, can sort the messages by conversation or by sending time.
• Export sms in both xml or txt format to either IsolateStorage or SkyDrive
  if you export sms to IsolateStorage, the exported file is export_sms.txt/export_sms.xml, you can use any IsolateStorage tools to download them to your computer.(The ID of this app is 09125ea9-95de-469a-aedc-22e35389ab0a);
  if you export sms to SkyDrive, the sms will upload to your SMS folder in SkyDrive

Download SMSBackup