Who is responsible for maintaining IIS for web apps?

Sounds like what you really need is someone with expertise on both sides of the fence.

In my experience (with smaller-sized companies), the IT/sysadmin staff doesn't have the time, interest, or webapp-specific knowledge to properly maintain IIS setups. They'll take things as far as the operating system and hand off IIS to me, the developer.

Obviously, I need to be "more than just a coder" to make this work properly; I have to be aware of system-level issues (security and whatnot). I've been doing low-level systems management for years so I'm confident with this sort of task (in fact, I've taught professional sysadmins a few things over the years). However, not every developer has this capability.

Still, from what I've seen, there are more developers with sysadmin skills then there are sysadmin with (webapp) development skills.

As always, YMMV.

I would personally not want a developer to mess around with IIS, especially if it meant that it might cause problems with another application with another developer having to trouble-shoot, on and on.

If there are IIS problems, have the SysAdmin look into it, and if there is a problem with a particular app, send it back to the dev. If the dev has an issue, bring it up to the SysAdmin, who can then attempt to make an informed decision as to whether to make any changes and figure out how it will affect everyone.

We (the sysadmins) treat our developers just as we would a 3rd party vendor - when they want us to deploy an app, they have to provide documentation if they expect it to be supported. This includes common troubleshooting routines and a support escalation path (uptime requirements combined with a documented developer responsibility in the case an unacceptable outage).

It's obviously not black and white, but it's done a lot to ease the tension between devs and admins. The devs now realize that they have to provide software of a quality inversely proportional to their willingness to be paged after hours, and the devs now have tools and docs to go through without feeling on the hook for tools they didn't create.

So, in your scenario, that would mean the devs create their app on their own IIS server and then provide the software and documentation for the admins to install on the production server.