Forms AuthWindows Auth – what is more common?

I was talking to some coworkers today about the scenarios for Forms Auth and Windows Auth in line of business applications.    We were having a debate about which was more common.

As you might guess at Microsoft we are an all windows shop, so just about all our line of business applications use Windows auth, and I gotta say it is pretty nice not to have to remember a bunch of user names and passwords.  

But I wonder if that is so common across the industry.. and even for companies that do use Windows Auth, I imagine there are scenarios where Forms auth is still important. 

One place this manifests itself is in the project templates  for things like ASP.NET MVC, ASP.NET WebForms, Silverlight, etc.  Should we be wiring these up to support Forms Auth by default (with a log in\register controls) or Windows Auth where those are not needed?

Here is a little forms auth example… 



What do you think?  What is more common in your experience Forms auth or Windows Auth?