There seem to be compatibility problems with Eagle from version 6 on, especially because Cadsoft has changed the resolution.
Someone has adjusted the file brd_to_dsn.ulp to Eagle 6 and uploaded it to the Cadsoft website at
The Eagle ulp-file on this website works only up to Eagle version 5
The author has now uploaded a more recent version of his Eagle 6 compatible ulp-file into this forum at viewtopic.php?f=6&t=222.
Please download and decompress the attached file there with name eagle2freerouter.zip instead.