Securing a webserver through reverse proxy?

[Security <security () zerouptime ch>]

Greetings,

I've read about a way to secure webservers, which must not be directly
exposed to the Internet, using a reverse proxy, e.g. MS ISA Server or
Squid on a UNIX box.

Now my question would be: Has anyone experience with that? Is it really
more secure (compared to firewalling and port forwarding)? Is the MS ISA
Server Webpublishing rule (which implies reverse caching) doing an
application layer filtering or does it just the mentioned caching? Can a
Squid reverse proxy solution fulfill that too?

If not, what are the steps necessary to accomplish this?

Your input is appreciated.

-- 
Jonas Nagel <fireball () zerouptime ch>