In IIS 6, using Perl, I was able to send a stream of output to the client rather than buffering the entire thing and dumping it out at all once. This allowed such things as progress bars and such to be used.
How can I accomplish the same thing in IIS 7?
Under IIS 7, once you have created the Perl Script script mapping, you can add an attribute that will fix this.
You modify the %windir%\system32\inetsrv\config\applicationHost.control file and find the script mapping by name (in my case, Perl-Script). Then add the responseBufferLimit attribute into the XML, for example:
<add name="Perl-Script" path="*.pl" blah blah blah responseBufferLimit="0" />
This causes IIS to run as it did in IIS 6, with buffering off.