I'm on a mac and just downloaded the latest dmg. As far as I can tell, gnucash support is not currently in the next branch.
I'm not handy enough with C/python to dive in and fix it, so I just whipped up a ruby script: http://github.com/xaviershay/gnucash2ledger It converts transactions (with reconciled status) and also commodity accounts. Works for me, YMMV Xavier
