IP on different subnet?

I'm not much of a network security expert but I have a question that
someone asked me the other day.

We all know the "i" can have multiple IP interfaces/addresses for each
NIC. If we were to set up a web server with it's own IP address would it
make sense (or even work) for the IP address to be on a different subnet,
or a different ip range all together?

Example:

Main IP 192.168.0.1

New IP 192.168.1.1 or even something like 10.1.1.10

My thinking is because there will be a firewall routing requests in from a
public IP to the web server IP address, the internal IP address doesn't
really need to be on a different subnet, range, etc, because that is all
invisible to the end user on the internet. And it may also take some
"tricky" finagling to even get things to work right for routing.

Thoughts?

Brad
www.bvstools.com