You can run Propeller GCC and SimpleIDE on any PC platform - Linux, Mac, or Windows. Visit Parallax's Learn website to download the latest version of SimpleIDE, which includes Propeller GCC.
At this point in time, the newest version of SimpleIDE for Linux is not yet available. However, a slightly older version of Linux SimpleIDE is available for download from SimpleIDE's Google Code site. It can be found here:
The Propeller GCC tool chain is also available as a stand-alone package. Please see the corresponding page for more information, or have a look below.
For advanced users, the Propeller GCC source code is available so you can build the Propeller GCC tool suite from sources. There, you can clone a copy of the current repository tree using the Mercurial Source Control Management tool. There are also many additional demo programs available there and prepackaged in the tool-chain downloads page.
Note: Though Parallax has made every attempt to streamline the build process, building the Propeller GCC compiler from source requires significant experience in configuring your Linux build environment. Basic build environment requirements and instructions are provided with the source repository.