You may find that exported DXF is graphical, more for documentation purposes than electrical implementation. Does Eagle import DXF as well? If it does, there is hope that the process isn't too lossy and enough electrical properties are preserved to be useful.
Historically, the more common ASCII format used for exchanging graphical/symbolic representations of PCB circuits between software applications has been EDIF.
I used to use it a lot between Protel and some in-house tools, back when I was reverse-engineering stuff at Chipworks. ;-)
My own personal preference based on more recent endeavours is something XML-based like SVG. It's a LOT easier to mark-up, filter, and massage an intermediate XML-based format using XSL Transforms, to handle those subtle differences between what one program puts out and the other expects, as well as write out to whatever destination format you need. The tricky part is coming up with the initial "db2xml" parser...
Disclaimer: I work for Cadence Design Systems, albeit on the semiconductor design software, so I choose to keep my distance with respect to downloading and/or using Eagle to check things out for myself. A necessary evil, unfortunately.