From Habari Project

Habari currently ships with a plugin to import posts, comments, tags (including Ultimate Tag Warrior Tags) and users from WordPress (current version confirmed to work with 2.7.1, mileage will vary with older versions). Other importers for Serendipity 0.9, Blogger, Drupal, and Movable Type in Habari's plugin directory.

You must first activate the plugin for the platform from which you are importing. Go to the Plugins page, click Activate by the importer you wish to use. After activating an importer plugin, it will be added to the list of other blog tools from which you can import on the import page. Then go to the Import page.

Important Note: Deactivate any spamchecking plugins or plugins that contact outside sites before beginning to import your data. If active, these will greatly slow down, or even prevent, the successful completion of the import process. In the case of spamchecking plugins, comments may incorrectly be marked as unapproved if a spamchecker plugin is active. Also be sure to not have any pingback plugins, or plugins like Twitter that send new posts as "tweets".

After you have completed the import process, remember to reactivate the plugins you deactivated.

Importing A Wordpress Database

After choosing to import a Wordpress database, you will be prompted to fill in your WordPress database information, and choose your options for tag importation.

It is suggested you set up a separate database for your Habari install from that of your WordPress installation. The import process will be much faster and has less room for error. WordPress pages should import as Habari pages, and everything else either an entry or draft.

Approved and unapproved comments will also be imported.

Note that WordPress permalinks and paths will be lost, and you should explore options with .htaccess if you are concerned with maintaining your previous links. Route 301 plugin may help in some cases, as will Raman Ng's RN Custom Permalink plugin. Alternatively, you can set up a custom permalink scheme by adding a rewrite rule to your Habari database. Feel free to post to Habari users if you have any questions or problems with your migration.

It is also recommended to minimize the amount of tables that are not part of the default WordPress schema. If you encounter any issues with your import, try backing up the WordPress database, and dropping or emptying any tables that are not part of the core WP tables.

Importing A Serendipity Database

After choosing to import a Serendipity database, you will be prompted to enter the version of Serendipity you are using, OR the location of the root web directory where the Serendipity configuration file can be found to gather version information. After entering this, you will be prompted for your database connection details, whether or not to import your Serendipity categories as tags, and whether or not to import unapproved comments. Enter these details, then click the Process with Import button to proceed.

As with Wordpress, your permalinks and paths will be lost. Explore the same options discussed above to maintain your previous links.