ReText README file clearly states "ReText is written in Python language and works on Linux and other
POSIX-compatible platforms." I expect this to work wherever Python and Qt run, maybe even Cygwin.
I see more and more of this as time goes on. Ubuntu is not the only GNU/Linux distribution! Hell, this program looks like it may run on any *nix that has Python and Qt.
The reason sourceforge is preferred by some people for binary hosting is that you get download stats. People want to know their impact. I think GitHub would really drive sourceforge out of business if they started offering this.
Ubuntu 12.04 ships with Python 3.2.3, IIRC the 'python3' executable is installed by default (even though the default installation may lack some third party modules).
I've been using this for a while (at least a year or so) and it's by far my favorite markdown editor. I love the side by side panes (code + preview) and the ease of use. It stays out of my way while I write.
I write Markdown for my blog and depending on what I'm doing, I like to write while I'm doing it, (to verify each step of a tutorial) which means I had to find a MD editor for 3 platforms (Windows, OSX, Linux). This one is by far the easiest, most reliable offering out of the three. The side by side preview is great.
I've used Uberwriter too, which would be great for a different kind of writing. Since I'm usually going through some steps of a tutorial I use a lot of images and code markup and it doesn't really handle this well. If I were writing a novel or article however Uberwriter works pretty great for that.