It appears that in the new hostapd (2.0+) that is on the ubuntu 13+ versions is now stopping on an error that it used to ignore.
(from https://stackoverflow.com/a/22845597/3495026 )
If one turns off the programs that are accessing the resource, hostapd has a chance to grab it and work.
In Ubuntu desktop 14.04 beta, a solution is to turn off the programs that are using the wlan in question.
This worked for me:
sudo nmcli nm wifi off
sudo rfkill unblock wlan
then hostapd can start normally from command line. Of course, if you want hostapd to start on boot you must insure that the network manager is not grabbing the resource ahead of time.