I filed this bug on 11-Apr-2007 (almost two years ago):

Title: Safari doesn't handle HTTP Content-Type header

11-Apr-2007 07:18 AM David Tanzer:
Summary: 
A HTML page which has the extension ".tar.gz" is automatically downloaded, even if the HTTP Content-Type 
header is "text/html". For example, the HTTP Headers for the page 
http://www.apache.org/dyn/closer.cgi/geronimo/2.0-M3/geronimo-tomcat6-jee5-2.0-M3-bin.tar.gz 
(which is a HTML page with the mirror list for the file) is automatically downloaded and NOT displayed as it 
should. The content type for this page is:

Content-Type: text/html; charset=iso-8859-1

Steps to Reproduce: 
1. Open the page http://www.apache.org/dyn/closer.cgi/geronimo/2.0-M3/geronimo-tomcat6-jee5-2.0-M3-bin.tar.gz

Expected Results: 
The mirror list for geronimo 2.0-M3 is displayed

Actual Results: 
The html file is downloaded and saved to the Desktop

Regression: 
N/A

It is still open, and the problem still exists in Safari 3.2.1 (5525.27.1). Good job, Apple.