I'm trying to import to a clean WordPress v3.0 and installed Textpattern Importer v0.2 and I'm importing from a Textpattern v4.2.0 blog.
I put in the information into the Importer text fields as they're recorded in my textpattern config.php file. I double checked my database details through phpMyAdmin.
The Importer doesn't take much time to think between 'Import' clicks and imports 0 items for each section i.e. categories, users, posts, comments and links.
Any suggestions of things I could try? This is all a bit of a black box to me. Any more information you'd like?