Is there a way to recover a deleted SMS?
If you use My Backup Pro and have regularly scheduled backups, you can retrieve your SMS messages, provided you've set them to be backed up.

Also see SMS Backup - it allows a user to backup the SMS directly into GMail, so you always have a backup away from your device - no harm even if your device is misplaced / stolen / not working and you need to refer to an SMS in a hurry.