How do you backup a blog?
For WordPress blogs, use the the WordPress Database Backup plugin. This plugin is included with all installs of WordPress starting with version 2 I believe. Once enabled, you just go tot he backups section of the manage screen, make a few selections and it’ll backup your blog posts to your desktop or email. I wouldn’t suggest backing up to the server as that won’t do you any good if your web server goes down.
For WordPress.com blogs, click on Manage and then Export.
With TypePad just got to the Import/Export area on the Manage tab of your admin area. Here you’ll be able to export all posts to your desktop. [backup support page]