Drupal - batch importing node data -- via database?

There are two routes you can take.

One uses the Migrate module usually in conjunction with Table Wizard. This gives you a web front end for doing an import with field mapping, and other nicities. EDIT: just saw that TW doesn't have a D7 version.

The other is a custom import script. The script does the Drupal bootstrap process, queries the remote database, creates a $node and then does a node_save. This is a little more complex, but not that hard.

I have been doing the later on new projects, and is easy to adapt to XML, CSV, or other data sources.