The officially released files can be found at: http://www.ethereal.com/download.html. A new Ethereal version is released, after significant changes compared to the last release were completed or a serious security issue was encountered. The typical release schedule is about every 4-8 weeks (although this may vary).
There are two kinds of distributions: binary and source, both have their advantages and disadvantages.
Binary distributions are usually easy to install (as simply starting the appropriate file is usually the only thing to do). They are available for the following systems:
Win32 (.exe file). The typical Windows end user is used to get a setup.exe file, which will install all the required things for him.
Debian (.deb file). A user of a Debian Package Manager (DPKG) based system is used to get a .deb file from which the package manager checks the dependancies and installs the software.
RedHat (.rpm file). A user of a RedHat Package Manager (RPM) based system is used to get a .rpm file from which the package manager checks the dependancies and installs the software.
Solaris. A Solaris user is used to get a file from which the package manager (PKG) checks the dependancies and installs the software.
However, if you want to start developing with Ethereal, the binary distributions won't be much helpful, as you need the source files, of course.
For details about how to build these binary distributions yourself, e.g. if you need a distribution for a special audience, see Section 4.13, “Binary packaging”.
It's still common for UNIX developers to give the end user a source tarball and let the user compile it on their target machine (configure, make, make install). However, for different UNIX (Linux) distributions it's becoming more common to release binary packages (e.g. .deb or .rpm files) these days.
You should use the released sources if you want to build Ethereal from source on your platform for productive use. However, if you going to develop changes to the Ethereal sources, it might be better to use the latest SVN sources. For details about the different ways to get the Ethereal source code see Section 4.4, “Obtain the Ethereal sources”.
Before building Ethereal from a source distribution, make sure you have all the tools and libraries required to build. The following chapters will describe the required tools and libraries in detail.