I've looked all over the place but haven't found a dhcpd.conf example with a directive like this in a single subnet:

range 10.0.0.1 10.0.4.1

Is this possible, or do I need to set up multiple subnets for each class of network address? I need to do this because I will likely have more than 256 users per subnet, though I suppose I could reorganize the topology across multiple subnets.

I have the potential for a thousand or so users getting DHCP leases from this box and I don't care to separate them into logical subnets...unless of course someone has a good reason to.

If you use a subnet mask of 255.255.0.0, 10.0.0.1 and 10.0.4.1 will be in the same subnet. With that mask, you could have over 65500 IP addresses on the subnet.
If you want about 1000 machines to be on the same subnet, you'll need to use a subnet mask of at least 255.255.248.0. That should give you around 1022 usable addresses on the subnet.

Most people don't use subnets that large but as long as you have the switch infastructure in place and your dhcp server can handle it, there's no reason you shouldn't be able to do it. It beats adding routers into your network if you don't need them.

Wicked, thanks !