The next release will feature signature support. I am still making a decision if I should include the UI for changing signature into ForumConverter or keep it seperate. So far I have built a BuddyPress and WordPress UI for modifying signature. Also, I still need to separate the signature assets/images into a separate upload folder within WordPress but currently it uses phpBB folders.
[Edit] I originally said attachment support, I made a mistake and meant signature support.