Wireshark currently runs on most UNIX platforms and various Windows platforms. It requires GTK+, GLib, libpcap and some other libraries in order to run.
As Wireshark is developed in a platform independent way and uses libraries (such as the GTK+ GUI library) which are available for a lot of different platforms, it's thus available on a wide variety of platforms.
If a binary package is not available for your platform, you should download the source and try to build it. Please report your experiences to wireshark-dev[AT]wireshark.org.
Binary packages are available for at least the following platforms:
Apple Mac OS X
BeOS
FreeBSD
HP-UX
IBM AIX
NetBSD
OpenBSD
SCO UnixWare/OpenUnix
SGI Irix
Sun Solaris/Intel
Sun Solaris/Sparc
Tru64 UNIX (formerly Digital UNIX)
Debian GNU/Linux
Ubuntu
Gentoo Linux
IBM S/390 Linux (Red Hat)
Mandrake Linux
PLD Linux
Red Hat Linux
Rock Linux
Slackware Linux
Suse Linux
Thanks to the Win32 API, development on all Windows platforms will be done in a very similar way. All Windows platforms referred to as Win32, Win or Windows may be used with the same meaning. Older Windows versions are no longer supported by Wireshark. As Windows CE differs a lot compared to the other Windows platforms mentioned, Wireshark will not run on Windows CE and there are no plans to support it.
Also the 64 bit Windows version are now supported by Wireshark. Although not all libraries are made 64 bit ready yet, basic operations are all available.
Windows Server 2000
Windows XP
Windows Server 2003
Windows Vista
Windows 7
Windows Server 2008