I wanted to make a comment about the text shown in the mockup there.
This part:

"which runs on Windows, Mac OS X and Linux"

Quite besides putting your fellow FOSS project last in a list of
supported operating systems, especially since many distros package and
release Inkscape ready to install and windows and macosx don't.
It's quite simply a question of popularity.   The list of operating systems goes by general OS popularity - and quite reasonably too.  Linux users will expect it to go in that order, whereas if you put Linux first, I think many Windows and OS X users would be put off it as "a Linux thing" that just happens to have been loosely ported to Windows/OS X.

But worse is the confusion of "Linux". Does this sentence mean that
Inkscape will work on Android? Will it work on my TiVo or my Home brew
Wii? It is nonsense to claim to run on Linux when linux is a kernel
which can't run Inkscape in most cases.

I disagree very strongly with your case here.  "Linux" is a generally recognised family of operating systems.  In the lingua franca, "Linux" means these operating systems, not the kernel as a technical definition of Linux may be.  And there isn't really any way I think it can be improved without it becoming too verbose (frankly I think even one word more in each of the places where Linux is mentioned would be too verbose, the brevity of "Windows", "Mac OS X" and "Linux" is important, and on your later points a group of three is in a literary manner far more pleasing than four or five items would be).  I don't believe anyone will get confused and expect it to run on any mobile browsers.  The downloads page will also have OS-sniffing and so present the most likely of the three options first, including highlighting the relevant option (e.g. Mac OS X 10.4 users will get that button glowing and the others slightly faded, Ubuntu users will get a sentence on how to get it in Ubuntu highlighted in some way).

It would be more clear and honest to say "which runs on Gnome/Linux" or
"FreeDesktop Linux" or just "Fedora, Debian and other awesome Free
If you start putting in some particular flavours of Linux then you get bickering about which ones get included.
And if you're of the opinion that Android and such aren't marketed as
Linux and there for won't be confusing. Think about the way Ubuntu isn't
marketed as Linux either (because it isn't true and because it's not
helpful to scare away new users), will we have "which runs on Linux and
Ubuntu" to account for that?
No.  Ubuntu is still recognised as Linux.  And putting this in combination with highlighting the relevant information on the download page, I don't think it'll be an issue.

The lack of consideration that Linux distros are given by the Inkscape
website is currently frustrating. The install for Windows and Mac is
easy, but we don't have a single deb, apt link, or ppa and instead ask
users to compile. Please consider rectifying and please start with the
text on the front page.
You're right about the need for more information on how to source Inkscape; I don't believe you're at all right about starting with the text on the front page.  What it says is correct.  The modifications only need to take place on the download page.