The RCP downloads are meant as a base for building Eclipse RCP applications.  
As such, they do not include an application of their own and simply running the 
RCP install will do nothing.

The Cocoa implementation of Eclipse 3.5 requires Mac OS X 10.5 (Leopard) or
higher, and Java 1.4.2 to Java 1.5.x.  Mac OS X 10.4 (Tiger) users can use the
Carbon implementation of Eclipse 3.5.  

Please use BOMArchiveHelper if StuffIt fails to extract the downloaded tar.gz
(https://bugs.eclipse.org/bugs/show_bug.cgi?id=131650).

In order to use the SWT_AWT bridge, OS X JRE version 1.5.0 Release 5 (or
greater) must be used.