I am also interested in this, i am / have been looking for a good captive portal and all the ones i have tried have some kind of flaw or dont work for an ip range i am looking for. I am wanting to use a class B subnet and have a wide range of ip addresses for my hotspots and subscribers, the reason being it would make it harder for the end users to be compromised by someone with less than perfect intents to hack their pc. as an example, i would have an ip range from 188.8.131.52 to 184.108.40.206 for self sign up users and 192.168.0.0 to 192.168.255.255 for customers with a 6 month contract. Would it also be to something like paypal wifi-1.1.1 prepaid, http://sourceforge.net/projects/wifipaypal/ , to the captive portal interface page. this is a relatively easy thing to use, but i ran into problems with the linux distro’s i had tried, not related to this software.
just a thought though