Ryan just posted the current development version of the wordpress site importer to github:
https://github.com/concrete5/wordpress_site_importer

When this is ready for showtime it'll be a free add-on.
This was originally written by ScottC, then GregJoyce picked it up at concrete5. It's status is described in the README in the code, but it basically works, even with really large imports, but it's formatting is a bit rough and the data that's imported is not complete.

If anyone has energy to put into it it'd be much appreciated.